That "8 plus" like SE phone was rumored before (it "should" have launched with the current SE, according to Prosser), the other ones are just guessing.
The in-display Touch ID was also rumored (for the next-gen of iPad Air), but I'm not really sure Apple is gonna step back in that direction. I mean it would be awesome, but for most people, Face ID works perfectly. Maybe Apple is gonna smartly combine Touch ID and Face ID into a "single" logging approach. If Face ID will not detect your face, it would try touch ID or something like that.
I have seen this Twitter account before and this guy is just guessing. Most of Apple fans could make guesses like that. We know what's going on at Apple, what devices need some refresh, what Apple launched in the past, what reliable leakers are saying. So we all are able to make some guesses that have a slight chance to become reality.