I would be surprised if he'll ever be back on the road. Even if the current virus gets under control he's into his 80th year & don't think he wants to risk his health or more importantly encourage mass gatherings furthering the spread of this current Pandemic.
Paul himself said that he wants to go back on tour (he said that in a instagram live to promote "McCartney III Imagined"). Of course, there's not much time left for his touring life, but when he turns 80, he won't automatically be unable to perform. Others from his generation, like Eric Clapton, Elton John and even Ringo, (who will be turning 81 in a few days) have already announced concerts for 2022.
If he is feeling good, I believe we should expect some shows next year. We can't predict Paul's plans, let's just wait and see what happens on the future.
For now, NYC is planning a big concert at Central Park on August and promoters want eight iconic stars to perform a three-hour show. Maybe Paul is gonna be one of these "iconic stars".