I think the smart money is that general relativity will be obsoleted. Or possibly be shown to be an approximation.
The most likely outcome, IMO, is that they will discover we actually live in some type of multiverse. Where the rules depend on what we're measuring, and how.
We need to get the dimensional stuff straightened out. It's very obvious we don't live in a four dimensional place, it's more like ten or eleven.
Even Einstein knew General Relativity was incomplete. It will be refined just as Newton's laws were refined by Einstein. But it should be noted that Newton's equations are still widely used. I don't know if obsolete is the right word.