Prior to the 30th Anniversary, I would have very much doubted any serious consideration had been given to a "Great Universal Movie Ride."
But since then, Universal has leaned into the nostalgia of their past in a much more pronounced way (the 30th merch line and continued retro items, the Legacy store, BTTF being part of the escape rooms, etc.). I still don't think it's anywhere close to likely (or as likely as I'd like!), but I no longer think it's impossible that it's at least been talked about interally (even in just a very informal way).