Hmmm..interesting.Not sure if he’s serious as Disney isn’t likely to just sit on a potentially lucrative property out of respect for the original actor.
The House of the Mouse has the last say.
https://www.ign.com/articles/2019/05/24/harrison-ford-says-no-one-else-can-play-indiana-jones-after-him-when-im-gone-hes-gone
Ford can say whatever he wants. If there's money to be made, Melissa McCarthy would play Indiana Jones. Bond didn't die with Connery's exit... although it could have and none of us would be the wiser.
For me, Ford will always be Indy. The next guy will just be Roger Moore.