If they have an exit strategy, I think that they do actually, this is what it probably looks like and the card will be played at the RNC in Florida, or at least that was the plan.
1. Trump can't resign in the middle of the pandemic but he also can't lose to Biden as that would destroy the 'myth' of Teflon don. So he announces he's not running for re-election due to undisclosed 'health reasons' he is willing to share but the family wants to keep private. Now it is clarified, this is not a mental issue or something that will kill him in office but something severe enough that it won't allow him from serving another full term. Through Axios a story leaks that is an early stage cancer.
2. With so little time left the Republicans default to Mike Pence but part of this deal was that Pence would pick a 'Trumpist' as VP, this can be Don Jr., Ivanka, Carlson, ... my money would be on Ivanka.
She has been with Trump on most foreign trips and while Jr. is an 'attack dog' he's also stupid and Trump knows this. Plus Jr. and Eric are both in charge of the company and the trust fund so they can't really do anything presidential in politics until dad is out of office.
3. They engineer a couple of 'health scares' so Trump is rushed to hospital from time to time to score sympathy points. Despite some hating his guts the media and Democrats find it difficult to attack a 70+ year old man dying of cancer and his grieving family.
Ivanka will give an emotional interview a month before the election and pleads that the nation allows her father to die in peace when the time comes.
A) Pence/Ivanka win the election
The plan works, the Democrats find it difficult to run Biden against Pence, who's simply more coherent. It's also hard to attack the GOP on women's issues with Ivanka as VP campaigning hard for the women's vote.
Which she also did for daddy in 2016. About 6 months into the administration Trump is magically 'cured' and plays an active part in the administration. Pence will be a one term President, Ivanka will be at the top of the ticket in 2024.
B) Biden/??? win the election
Trump will say he didn't lose because he didn't run and that Pence is a total loser and his daughter should've been at the top of the ticket. Like he did with the Obama/Romney race he will just keep blaming Pence for the loss, saying that he would've won bigly.
Within 6 months he is declared 100% healthy again and his next grift begins. Ivanka and Carlson are the front runners in the Republican primary of 2024.