For something to happen at DHS, it would have to be a land de novo, like how Carsland was built on land that was not a guest area and did not have attractions, i.e. a parking lot. Perhaps not surprisingly, if you want to fill a theme park with more guests, you have to expand it, rather than change around attractions.
DHS attendance went up, getting near 10 million a year. In fact, all of WDW's 4 gates are up. If WDW's attendance goes up a miserly 2% a year, in five years that's about 5 million more guests . . . not even Carsland at DCA can accomodate that many guests a year. If you take out Backlot at DHS and replace it with something else, the improvement in guest/ride/restaurant capacity is a joke.
At some point, beyond guests paying disabled people to avoid lines, guests will get sick of having to pay more to get on fewer rides, and Disney will have to decide between building a couple lands on unused space or the fifth gate. Probably a fifth gate given that that would allow for 6 million guests to be swallowed up, and more as the park expands.
You'd think that Orlando isn't a hot area for growth in the theme park industry, certainly the rumblings about Brazil make sense, but WDW is also a cash cow that will have steady growth in the coming decade. Disney just has to decide where to put the money.