When i was going into d3 i was completely ignorant about ARPGs and i envisioned it as Lost Ark currently is, where i go in lvl up my char, do dungeons, do bosses with interesting mechanics, collect stuff, do pvp, etc. It was nothing like that and i detested it.
However, Lost Ark is not successful yet in the global market, people are thirsty for new MMOs but they don't play for more than a couple of months as we have recently observed with SOLO, NW & Blessed Unleased. Lost Ark has released less than a couple of months ago, i currently play it and i like it, but i don't see it being very successful in the long run, its player count has already decreased by a lot, which is expected, but many people will soon realize that it is just not worth it to pay so much money on a "free game". I bought the platinum edition because it is a game that i greatly expected for years, but i won't pay any more money for at least a year, i don't care about progressing fast and if i cannot reach Tier 3 (endgame) within a reasonable timeframe i will probably drop it and return to either WoW or FFXIV or GW2.
It is very hard for a p2w game to be successful in the west and for the better, nevertheless, in order to return on topic, a good Diablo game that plays like Lost Ark, it is not free, but has some microtransactions, to keep development going, that are not predatory can be very successful. But as another one here said and i completely agree, isometric camera is a bit of a turn off for MMOs and i don't think that any game no matter how good it is can become a giant of the MMO industry with that camera style.