PvP in an arpg is a very marmite thing, many people don't bother with it, specially the "hardcore" players.
There are world bosses, on a week long lock out so not something that can be repeated at will, unlike for instance Last Epoch boss content, or Path of Exile pinnacle boss content which can be done as often as you want, as long as you have the encounter fragments.
If dungeons are going to be the D4 "map or monolith system" then as they are currently will be extremely dull and repetative after a short time.
Try doing all 23 dungeons in act 1 currently, by the time your half way though you'll be bored, now try repeating them 100 times. Blizzard did say they would be going more into detail about endgame after the beta, not sure if its this week or next, but it will clear things up because long term I don't see D4 lasting much beyond its campaign and new game ephoria.
The whole collectible aspect as well, could be an issue, specially if they are not account bound like the lilith statues, imagine having to repeat that rubbish every single season. There's 28 of the damn things in the act 1 zone alone.
I'm not trying to be a debbie downer here, I'm just not blinded by the "ohhhh shiny" aspect of a new game. Yes its good, yes its fun, and yes I will be playing it, but beyond the campaign I don't see how it can be a long term thing like the 13,000 hours I have in PoE, or the 600 hours I have in Lost Ark, or the 200 hours I have in Last Epoch. There just isn't enough depth or complexity in any of the systems I have seen so far, including from leaked footage last year.