Time will tell of course. Andrew McCarthy, a writer for National Review and former federal prosecutor, also thinks an indictment against Trump is likely.
I think the threat of professional sanctions would stop most prosecutors from filing overtly frivolously charges. For the most part, local prosecutors have laid fairly low in regards to Trump. Most State and local prosecutors are not going to take on a sitting President, unless they having something particularly damning and egregious to run with. And typically, State and local prosecutors defer to Federal prosecutors in these matters.
I don’t see State and local prosecutions as being a major issue for a President, since any impeachable matter is likely to carry an underlying Federal criminal offense, not a State or local charge.
Where I DO see the State and local folks entering the picture is in a post-Presidential situation where Trump has pardoned himself of Federal charges. Trump or any President cannot pardon away State or local crimes, so if they have something, that is when the State and local prosecutors would likely pounce.
We should look were we are at today. BOTH major party Presidential candidates were AT best ethically compromise and at worst, both could very well be guilty of felony crimes. On that we must wait and see.
Is this really what we want in our candidates?
An easier path to prosecutions against sitting Presidents might incline the Trumps and Clintons of the world to step aside and more upright candidates to come forward.
Deferring prosecutions enables criminal behavior to at least some extent and that is not the path we should be on.