Mitch gives off lifer vibes so I doubt he retires, especially if Rs take back the senate. Either way he will very likely be primaried out.
It's hard for me to imagine Mitch being primaried.
What makes you think it would be very likely?
He's extremely unpopular and this time the MAGA people want him out.
Republicans in primary races across the country last year (even establishment ones) made sure to distance themselves from McConnell, even Daniel Cameron distanced himself from Mitch.
McConnell has also been making more bipartisan votes and votes clearly against the Trump wing. If he cared about being re-elected he wouldn't be saying stupid things like "winning the war in Ukraine is the most important issue for voters" or openly criticising Trump whenever he's brought up.
Mitch is more disliked among Republicans than Sinema is by Democrats. Look at the Republican presidential field, do you think any would seek a McConnell endorsement? Maybe Pence or Hutchinson, but otherwise he is seen on the same level as Cheney now.
As for his "machine", George P. Bush got destroyed in Texas by Ken Paxton because his family became seen as an anti-Trump family, despite him sucking up to Trump and denouncing his family. I saw quotes by political strategists about it that said "no Bush can get elected in Texas anymore". Machines don't work when you're as hated as Mitch.
This isn't a Kemp situation where the only disagreement he has with Trump is the 2020 election (and Kemp never criticised Trump). McConnell (as silly as it sounds to Democrats) is essentially seen as bad as a Democrat in the eyes of most Republicans. And not just online people.
If McConnell ran for re-election, I'd not be surprised if he struggles to break 35% in his primary.