He will of course leave the primaries and throw whatever support he has behind DeSantis in exchange for a position somewhere.
No.
He exists in the race to hinder deSantis and empower Trump.
You need to understand the globalist establishment is terrified of deSantis, moreso than they are of Trump, for a few reasons. The first is that deSantis has a proven record as governor and has shown time and again he's willing to go against the establishment sacred cows, like Disney, and has also shown he can win. Further, he's surrounded himself with competent people which will enable him to build a cabinet that actually reflects and enforces his policies if he became President. Further they're not sure they can beat deSantis in the general election. He doesn't have the negatives that Trump did (and for those saying, "just let the mainstream media have at him and he will, you need to go look at the negatives for other recent Republican presidents whom the media gave the same treatment to. Also consider Hillary Clinton who had equal if not greater negatives than Trump DESPITE a fawning media. Candidate personality and history matters A LOT, the media can only do so much.) and they will have a much more difficult time rallying the people needed to fortify an election against deSantis.
Meanwhile Trump, they're sure they can beat him in the general. He still has those negatives and they can rally the same people and "threat to Democracy" narrative against him to enable election fortification in a way they can't against deSantis.
Basically, the globalist establishment, if they cannot have one of their own as the Republican candidate (which at this point they cannot, Republican primary voters have gotten too canny and too burned by the past) would rather have Trump because they believe he cannot beat Biden and even if he did have a chance, they believe they can fortify things to counter him because there's enough of a panic and emotional response against him to motivate people.
Now, they may be wrong. After all, that was similar to their logic in 2016 and why they enabled Trump over other Republicans and we saw how that turned out. But that's the actual gamble going on by the Globalists.