Yes, I suppose it means easier since the difficulty curve is smoother. Previously it was like very steep steps. Now it is steps with the occasional ramp. I would not consider it casualising. All of the game’s previous challenges remain the same.
I doubt everybody is going to exclusively farm two dungeons, just as they do not exclusively farm Port Valbury. This update simply catches up the older roguelike dungeons to what’s offered in the newest one.
Plans after the expansion depend entirely on how well it does, whether there is a second expansion or not.
I somehow doubt anybody in the office is interested in working on an MMO anytime soon, never mind the insane budget and development time those involve.