Folks, I have done math.
First: shout out to our good friends at Touring Plans
for the hotel room data.
Second: Here is the spreadsheet I put together.
Here's the too long, didn't click on the spreadsheet link. Right now there are 28 Universal Orlando Resort attractions with Express at the two dry parks and there are 2,400 rooms that grant occupants Unlimited Express. That will increase to 2,900 when Epic Universe opens.
Right now there are 0.0117 attractions per guest room. When Epic Universe opens (along with Helios) there will be .0097 attractions per guest room
if Epic Universe opens without Express. If Epic Universe opens with Express at eight attractions (listed on the spreadsheet), we'll actually see a slight improvement to .0124 attractions per guest room.
Some caveats: This doesn't tell us anything about occupancy (how many total guests each hotel can hold) and obviously I'm making an educated guess regarding which attractions will have Express.
My takeaway is that even if there are no changes to Express when Epic Universe opens, it's unlikely to be catastrophic at either of the two existing parks. And I think
@fryoj is 100 percent right that if Epic Universe offers Express, it'll be mobbed. Which is why it probably makes sense to not open with Express, though I'd be a little ticked off as a Helios guest if that is indeed the case.