Indiana Jones movie not going to happen...
... and I'm good with that.
i. Ford is 78. COVID has shuttered the movie and cinema industry, probably for another 12 months at least. By the time the movie was ready to roll, Ford would be in his early 80s.
If they have a story where Indy plays his age, who really wants to see a croaky-voice Indy shuffling around? We wanna see whip-cracking, two-fisted Indy. Even de-aging technology can't disguise the age of the person under the digital makeup... they still move like old men.
ii. I've read that Spielberg and Lucas have left the project for others to carry out the directing and producing chores. The trio worked like a well-oiled machine and I doubt that on-set magic can be re-created with new people in the roles.
iii. The recent death of Sean Connery -- Henry Jones Sr -- must surely have Ford meditating on his own mortality. When your remaining years can likely be counted on two hands, the idea of working on a movie for two years suddenly doesn't seem meaningful.
One way out of this conundrum, it to simply use an elderly Indiana as a framing device for a movie that goes back to the late-30s and 40s. This could be the means by which they re-cast the character and continue the adventures with a different actor. Ford's participation would be limited to a week or so.
Personally, I think it would be fine to simply retire the character. We had three great movies...