That is the current rumors, that they will have three. It does not sound, again from what rumors have come out, as if the SE will be upgraded this year -- not sure if they won't upgrade it or are just going to wait another year.
As jlczl stated, the rumor is that the "iPhone 8" will be more than $1000, which might limit its demand (at least a little). It is rumored to have an OLED screen (the other two will retain the current LCD screens), which is part of the reason it will cost so much.
From what I can tell, Apple is currently making at least six iPhones; and that doesn't count the various color, memory, and "carrier" (radio) versions. Obviously they are manufacturing the 7 and 7 Plus, and the iPhone SE. They also seem to still be building the 6 and 6 Plus, and oddly, are still manufacturing the 5s. I just purchased my 5s; it is brand new and (looking it up from the serial number) appears to have been assembled in January, 2017. Supporting the idea that it was built this year, it came with iOS 10.2 out of the box -- I upgraded it to iOS 10.2.1, and now to 10.3 beta.
Exactly so many configurations already. I don't see a pro being released myself; 10th anniversary or not.
Time will tell I mean in the future it wouldn't surprise me if the devices continue to have features dependent on size, such as the two cameras on plus model now to one on non plus.