Yeah they didn’t come out and directly say it. But they said enough that you can make a conclusion of confidence that At least Diablo will be coming in an expansion.
Stuff Inread says nothing of sales. It was all lack of monetization revenues and declining interest was the reason for the plug to be pulled. Some devs were cited as saying they wish the exec’s wouldnhave waited for RoS reception before canning the second expansion.
You are right the zones, mobs, boss, and Necro are all stuff that just wasn’t happening with seasons, then a big drop of this stuff for a while when it was never done before, and it was well known resources were shifted to D4 for a while now. There was a second expansion in the mix. Top bass jumped the gun.
No in D2 cow level was made in part cause if the cows in D1 but they put thought into it and made it a good place for xp, great place for runes , great place to find base items needed for crafting. D3 DID IT AS A COMPLETE JOKE with zero thought put into it.
Yeah, I mean…why aren’t we just playing table top games still? Why make computer games at all right? 
We are all going to die, so why bother doing anything? Did I do that right?
Cow level and Whymsidale/shire are just as good of places to farm exp as any other map. Why is has some unique rare mobs and special wings. Hell even the puzzle ring is a great place to get gold fast if you need it.
As if there was no thought into the joke places in D3. Of course there was. So tired of the O don’t like something therefore the maker are lazy, stupid, incompetent, or are just greedy line of thinking.
No one wants a Diablo 3 expansion. Diablo 3 had a very rough launch. By the time Diablo 3 was in a good spot, around the release of ROS, the damage had already been done for many. The decision was made (as far as we have been told) at that point to cut the Diablo 3 losses and begin working on Diablo 4.
I think at this point its a new base, a redemption from Diablo 3. The vibe I got from Blizzcon was to create a worthy successor to Diablo 2. Take the good they learned from Diablo 3 and dare I say it WoW - and build a new, better, Diablo experience that can’t be done with just an expansion.