I haven't heard of anything, but my guess is there really won't be much happening. There might be some new merchandise (Disney almost never misses a merchandising opportunity), but as the PP said, they already rolled out the lightsaber churros and new merchandise for May the 4th. I would keep an eye on the Disney Parks Blog for any announcements, but I wouldn't expect very much. May 25th is two days before the Summer of the Heroes promotion begins, so most/much of the attention will be on the new GotG: Mission Breakout attraction and other Marvel related activities.