No, nobody has actual access to the contract, but I've always heard (like since Simpsons was built) that it was 2028 like
@DodgsonHere said.
Also, there are more than rumblings about Simpsons being removed in Hollywood
The Universal parks are normally downstream from one another, so it's not surprising that someone would deduce that Simpsons would be on the chopping block soon-ish
Add in the fact that the BTTF ride system is as old as...well....me...and I'm 30 - at death's door
Personally, I think this land will be rethemed to a property that hasn't been invented yet...I guess we'll see