So what's gonna happen? We don't know. I think there's a 1% chance that Blizzard is doing anything along the lines what I pointed out in the previous paragraph for D3. There's a bigger chance (say 33%) they're working on D4. There's about an equally big chance they're working on a reboot (DEMONS VERSUS ANGELS F2P VR MOBILE MMO or whatever; I don't really care what they call it as long as they stop this "Nephalem" bullshit, imho). And then there's a chance - like you said, Aerisot - of them doing none of this and just letting the franchise die. The Diablo 3 job posts could easily just be for recruiting purpose and the new game could be something entirely different. Like an casual, clicker-based MMORPG in the Overwatch universe. Or whatever. :-)
I personally liked the Nephalem theme, maybe because i releated with the Nephilims and i just love that concept.
Few things that are wrong are the difficulty curve (you put set items and go from T3 to T13 in an instant), no difficulty cap, too much powercreep and it needs a bit more depth in the item system/endgame content.
Microtransactions are the worst thing you can do to a game that you pay 60 dollars to start with. It's just overgreed from developers unless it's a F2P game. I'll definetly remember when games came with all the customization included or at most with a 15$ DLC cost instead of the gambling RNG lootboxes that are never going to give you what you want.