Russian emails? Are you thinking of the Wikileaks stuff, with the hacked data from Clinton's campaign staffers? I am pretty sure those are different and separate from the emails that Comey was investigating for the FBI.
There are two "Hilary's emails" stories. It is easy to confuse the two -- Republicans worked very hard throughout 2016 to make it easy to confuse the two -- yet they are two different series of events and almost totally unrelated to one another.
The original "Buttery Males" story: Comey and the FBI investigated emails that were stored on a private server owned by the Clinton Foundation, a server that Hilary had used for official business while serving as Secretary of State. In July of 2016, Comey announced that while they did find a small number of documents marked "classified" stored on the server, this violation was obviously inadvertent and should not be prosecuted. "Sloppy but not criminal," or something like that. Then later in October (after taking a few months of heat from his fellow Republicans for not going after Clinton harder) Comey announced that there may be files on a laptop owned by Hilary's assistant, Huma Abedin, that the FBI had not yet had a chance to review. Comey announced this privately to a congressional committee and it was leaked almost instantly, about a week before election day.
The "From Russia with Love" email story: Meanwhile, Russian hackers infiltrated Hilary Clinton's 2016 presidential campaign and stole thousands of personal emails and other data from her staffers and people they'd communicated with. None of these emails were classified and the FBI never investigated the Clinton campaign in this case (except as the victims of a crime). Wikileaks and Julian Assange got in on the action and built up lots of hype. That's when, in the middle of a campaign speech, Trump made his famous on-stage plea: "Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing. I think you will probably be rewarded mightily by our press."
Trump was clever, mendaciously associating the original "classified documents on your private server" controversy with the "Russia stole your data and is about to release it on Wikileaks" controversy, but the two stories don't really have anything to do with one another, at all, and they never really did.
It may even be to their advantage, as the new candidate receives Trumps blessing and gives Trump clemency.
I also have been wondering what the race will look like in six months, when all this speculation about Trump's trials (and potential prison time?) will be upon us for real.
Legally (so far at least) they say Trump can run from prison. If he were to win, as POTUS he'd have many options available to clear his name, dismiss his accusers, and attack his opponents.
I don't think Trump will give another candidate his endorsement, even from prison. If he does, it won't be without that other candidate publicly swearing fealty and promising to grant clemency, as you say. The way I see it, any candidate who'd be willing to do that will look weak and subservient, and probably look worse than Trump's going to look, even from prison, by the time they get to the general election.
I think the only way another candidate wins the GOP nomination is by taking it from Trump -- not by Trump lending it out to them.
