So, I'll make a big response.
To start with, I'd dispute the claim that 'virtually all playtime will be spent in endgame'. What does endgame mean to you here? Sitting at max level and killing the same things over and over again?
Because if that's what you mean by endgame, then you are absolutely right, we don't have one. I mean, you can do that. We have random maps and we allow you to NG+ ad-infinitum so that you can whack things to death at level 100 to your heart's content. I don't think that's fun, or something that I want to be doing, so we aren't making a game that focuses on that. We want you to play the game AGAIN. That's the point of randomization. That's why we don't allow full respecs. That's why we built a ridiculous amount of randomized content so that your next playthrough feels fresh, and not like a complete retread. What's the 'endgame' of Nethack?
To be clear, I understand that many people enjoy that. That's fantastic, and there are MANY games that cater to that specific need. But we aren't, and never will be, one of them - nor have we ever pretended to be, or aspired to be.
Official word on PVP - we've had an official word on PVP for ages. Our official word is and has always been, it's sort of there, you can do it, and we allow you to flag regions as forced-PVP if you want in mods, but it isn't the experience we're making. We aren't balancing our skills around killing other players - we're balancing them around killing hordes of monsters. Those are very different things.
Cheating. We have again maintained that we are NOT providing a closed ecosystem. Again, there are other games that do this - and they were willing to shoulder the tradeoffs that you MUST MAKE to provide this. We weren't interested in those tradeoffs or that burden. They were not in keeping with the kind of game we wanted to make. We have never pretended or proposed that we would make a closed game and have been at great pains to make sure that people understand we are NOT providing it. We have endeavored to give you tools to play with only the people you want to, and to eject cheaters from your game and never see them again.
The idea that mods somehow reduce the longevity of a game is something I don't understand at all, and can't think of a single instance of it being true, ever. And EVEN IF IT WERE TRUE I WOULDN'T CARE! I like mods.
If the idea of another person cheating at a game invalidates all of your enjoyment of the game you are playing, I don't even know what to do with that. How does anyone ever enjoy a game of Solitaire? I mean, you can just TURN OVER THE CARDS! The rules are not enforced! How can anyone read a novel? You can just FLIP TO THE END! More to the point - anyone out there in the world could be flipping to the end before you!
If a strictly enforced online environment that prevents any other player from cheating or modifying the files is required for your enjoyment, then this game will NOT be fun for you I guess, and that's ok!
That's not the game we made. I'm all right with that.
We don't need the game to provide unlimited replayability for all time in order to feel that we succeeded at our goals, or for this to be successful for us. We think it's really fun, and super-replayable, and we like it and enjoy playing it. That's enough for us.