There is not a chance any carrier brings back a 2-year contract. They are making more money with this structure.
You bet they are. I'm still paying AT&T the same price (now $10 more, really) for my grandfathered unlimited data plan that I've had since 2009, even now that I'm newly off-contract (from my last one with 2015's iPhone 6s Plus) and nothing being subsidized at all (nor ever again, it appears).
AT&T is effectively making $20 extra from me a month now for nothing, compared to the normal $20 access fee it charges others without the grandfathered unlimited. In fact, if I got on to one of AT&T's standard plans, it would cost me the same $80/month for a 6Gb mobile share plan (with $20 access fee for one device) as it is with my current setup ($35 voice + $5 text + 40 unlimited data / access fee). And I'm not even using over 4Gb per month. Ridiculous.
I'm NEVER buying a phone directly through AT&T again. I'll only be purchasing a SIM-Free (or Verizon-capable) iPhone from Apple, and reminding AT&T that I'm a free agent and may leave them if I even simply roll out of the wrong side of bed one day.