Many people who have a special interest in seeing the Muslim Brotherhood fail are taking clues from the various mistakes of the Ikhwan as being a sign of a fall to come. They are interpreting the results of the first round of presidential elections (compared to those of the parliamentary elections) as a clear sign of how much ground the MB have lost since January 25th. Many would like to believe that all the Brotherhood mistakes, their lies and their cheating over the past year and a half are exposing them and have taken a big toll on their popularity in the streets as well as with politicians and activists. That might be true but it has not made them any weaker.
First of all, in consideration of where the MB were before January 25th, they have come a long way. From being an illegal organization, they are now perceived – both locally and internationally - as the only organized political power capable of filling the vacuum that was left by the fall of Mubarak. They now have formal offices all over the country, access to media, contact with the various international powers and definitely a major say in what happens in Egypt, even with the SCAF in full or partial control. That's why, everything considered, they are now in a much better position compared to a year and half ago.
Second, they have a huge and obedient follower base (some people put it as high as a million "brother") and lots of funds (that get replenished monthly from members' contributions). Mistakes might cost them a lot of money but they are able to dedicate significant resources to mend such cracks. This access to resources is unparalleled by any organized power in Egypt except for the army.
Third, they might have lost the parliament but they still managed to get the presidency. Morsi could end-up failing miserably as a president, however, who said that they were seeking immediate power? The presence of one of their own in the highest executive position gives them the chance to plant their own people in every corner of the government, giving them the sort of grassroots control they're so crazy about. Especially, when they start penetrating critical government organizations such as media, municipalities and the social welfare ministries, which is their key strategy in rallying voters. Their control on the lower level of the government gives them as much power – if not more – as being at the top of the pyramid. It will be a matter of time until they are able to grip the whole government and operate this machine to serve their interests. Moreover, in the constitution they are writing (almost entirely alone, save the few clauses the SCAF had asked for), they will transfer a lot of the president's powers to the parliament and other organizations in the government. If Morsi fails, it will not matter to them, they will not seek another presidency and will continue to run the country from those other organizations that have gained those powers.
Fourth, their coming to power creates a snowball effect. Many people will join their circles and support them in order to benefit from their access, this will make them gain more power and make them more appealing for even more people and so on and so forth. Businessmen will seek their partnership, journalists will flatter them, and so on.. It's very similar to what happened with the NDP; many joined it not because they believed in what it stood for but rather to benefit from its network of interests.
Fifth, until today, there are no other viable political alternatives that have emerged. Liberals and leftists could go on hating the MB as much as they like but the truth of the matter is that these political parties/movements have no presence on the ground and lack the resources needed to compete with the Brotherhood. Moreover, the more power the Ikhwan amasses the fiercer they will become in oppressing any opposition and kill any threat in its inception phase. They will use the media, buying off politicians, bribery, loyal judges and eventually the police to oppress; a very similar model to Mubarak, maybe not as bloody in the beginning but they definitely carry an identical mentality.
You have to give it to the Brotherhood, they are persistent and they have enough resources to afford making that many mistakes and still get away with it. They might be slow learner but again they have more than enough money to pay for their faults. They are long term planners and are seeking complete dominance of this country. In the process they might have to shed a lot of their ideology and seek compromises, they might turn into just another political party with the Islamic reference becoming nowhere to be seen except in their literature. However, that will not change the fact that they will not stop before having complete control of this country.
The only way that the Brotherhood "might" fail is if it cannot restructure itself internally. The organization right now is extremely opaque, the top level positions in the MB are restricted to a Brotherhood "elite" that pretty much revolves around Khairat El Shater and a couple of other key figures, who distribute the positions to people they "trust" rather than those who are capable. Being run like a family business means it will suffer the same fate: incompetence on the medium and long term and discontent from the middle ranks who will realize that they have no room to grow. Additionally, the lack of transparency with regards to the MB's finances will eventually cause cracks in the organization. Now that the Brotherhood is coming to light, the hundreds of millions of pounds that run every year uncontrolled and unmonitored will eventually raise questions on what El Shater and Co are doing with this money. If and how the MB might restructure itself will determine if it will be able to carry on with its plans or not. But that is something neither the liberals nor the leftists have any control over.
The MB have lost nothing in the past year and a half. Au contraire, they have gained a lot and they're braced to take control of this country. In the absence of any organized political and social opposition that will ensure that a transparent and fair political system is put in place, the MB will dominate this country within the coming 10 years. Their real failure will come probably 30 years from now when people decide to rise again against them, for pretty much the same reasons why they did it with Mubarak; because monopolizing power is the surest way to fail.