I don't think there's a good answer because any answer to your question hinges on a political decision. From a practical point of view, "holding him accountable" requires a group of politically-minded people to agree that he has committed a crime for which he needs to be held accountable.

Let's say, for the sake of the argument, that there is indeed a law that he has broken. If the people with the power to punish him for it decide not to do it, then whether he actually committed a crime or not is a moot point. We will only know whether he will be held accountable once he is being held accountable.

Not an answer, exactly, but there is talk of invoking the 25th amendment (possible I suppose, considering Pence and Trump are at odds currently). As of now, none of Trump's cabinet nor Pence have suggested intent to do so. I would wager it will take another event of this nature and/or a big hit to Trump's approval ratings which are very static and unchanged by scandal mostly.

There's also the option of impeachment and removal. This is significantly less likely as it requires a majority of senators and Trump only has two weeks left.

It's unlikely he will be held accountable for encouraging domestic terrorism against democratic and republican lawmakers alike. Especially if he wins up pardoning himself.

Edit:

CNN just reported a source claiming some of Trump's cabinet are in early talks about invoking the 25th amendment. Still very unlikely to happen however.

The best thing we can do is not let history forget what happened today, and what will happen with we let someone like Donald Trump have free reign over the political institutions without proper checks and balances. More than ever, the Democrats need to limit their own powers to prevent a similar occurrence in 4 or 8 more years.