The two SW:GE attractions are the very definition of E-Ticket. MRR is debatable, but since it stars the Mouse himself, it gets a push in that direction. Guardians definitely. Tron definitely.
So 4 new E-tickets opening in the next few years. What are the last four to open before these 4? FoP, SDMT, FEA, Everest? Thats calling FEA an E-ticket. Everest opened in 2006. Meaning it took 12 years to get those four open, and we're going to see 4 new ones in a roughly two year period. If you don't count FEA, then you're going back to 2003 for M:S. Point being this is an unprecedented build out for WDW. Like I said you can debate MRR, but if you count Frozen, you have to count MRR. And MRR makes 5 E-tickets opening from say mid 2019 to some time in 2021. I'm just assuming they will have Tron open for the 50th.