Super long post warning.
I've read the indictment. I don't think Fani Willis is a very good prosecutor or at least this isn't a very good indictment.
The best criminal cases you can build are the ones that are as simple as you can make them. Defendant did x, this statute says x is illegal, Defendant is guilty. This is why I think the documents case against Trump has the highest likelihood of success. There are clear, discreet acts with matching statutes. The indictment in that case was very tight and specific. It makes the case much easier to try and much easier to win.
This indictment is messy. First, to get a racketeering charge you have to show the enterprise was trying to achieve an illegal purpose. Some illegal actions by members of a group trying to do something legal will not make the entire group a racketeering scheme. It's clear that Willis wanted to charge Trump with overturning the election. That's a political decision for Willis, not a tactical one. Her problem is that attempting to overturn a presidential election isn't illegal in Georgia. So it can't be the basis for a racketeering charge.
Willis instead had to try to hang the racketeering scheme on soliciting public officials to violate their oaths of office. That is a very difficult charge to prove and some of her counts have major problems of their own. Willis went after several instances of trying to get various officials to call special legislative sessions to choose new electors. Those are going to be difficult. Calling special sessions to debate whether to try to choose new electors is something that's within the discretion of those officials. They might ultimately not be able to do it but they have the power to try and then have a court tell them no. If you lobby a legislator to make witchcraft punishable by burning at the stake that doesn't make what you did a crime just because the ultimate end would be outside of the legislature's power.
The attempt to get the Georgia secretary of state to violate his oath of office is another difficult charge. I have to stop here and say I'm basing this on what we publicly know. It's possible Willis has some evidence she's not showing yet that could change things. But based on what's publicly known about that phone call, this charge is very difficult to prove. Everything we know Trump said can be explained away as Trump trying to get the Georgia SOS to do legal acts within his discretion that Trump could have thought might change the result of the election. The statements can be interpreted as Trump soliciting illegal acts too but the burden is beyond a reasonable doubt.
If Willis can't prove the counts of soliciting the violations of oaths of office, the racketeering case probably falls apart. The enterprise turns from being one illegally trying to manipulate state officials to one of trying petition state institutions in an attempt to win an election.
I'll stop here to touch on the fake electors issue. Sending alternate electors is something else that's not technically against the law. Trump can say that the process in Washington has to certify which electors are valid and they were there in case the process decided the official electors were not valid. There are some problems for some of the fake electors as they potentially committed forgery in the process but this is another point where Willis has a problem of what she wants to charge not being technically illegal.
If the racketeering charge falls apart there are still some things that could go forward but it will be difficult to get Trump on them. A lot of the remaining counts can be pawned off on lower level people who were overzealous in what they were doing. They can be characterized as not the actions of the enterprise but the actions of individuals.
Another problem Willis has is the fact that she charged so many people and put together such a complex timeline. Every defendant you add multiplies the complexity of a case. The more events you shove into a timeline, the harder it is for prosecutors, much less jurors, to keep it all straight. If the case is too complex for the jury you risk them acquitting the defendants as they wont think the prosecutors have proven their case.
One thing that is in Willis' favor, and it's potentially a trump card (pun intended), is that with so many defendants and unindicted potential defendants, you increase the likelihood some of them will roll. I don't think one turning will be enough. It will probably take flipping a couple but I think the strategy is to indict everyone and put pressure on key players you think you can flip. If the defendants keep a united front and Willis isn't holding crucial non-public evidence, then Willis' case is in trouble.