There's no point in a remake in my opinion, because arguments and splits will form within the fanbase over exactly what improvements are necessary and how they should be achieved. If it's one of those remakes which plays identically to the original and is almost 1:1, but with much prettier graphics, then what's the point?
On a personal level, I would love them to be remade for a bunch of changes/improvements to be made. I'd love Shenmue 1 and 2 to be streamlined as one game if that was an option, but I'd also love for new scenes and for changes to be made, in a similar way to how the anime handled it. I'd love for aspects of the gameplay to be modernised and changed. I would love, for example, for more puzzles to be added. I wouldn't even complain if the fighting system was radically changed, as long as it's good.
I'd even be intrigued if they went the FFVII Remake route and just drastically changed loads of stuff.
But I know a lot of people are very protective about Shenmue and would be very against messing with it.
The risk with all these side projects like Shenmue 0 and remakes is that they mess them up and produce bad games, and they bomb. Or maybe they actually produce decent games and they still bomb. And either way, it is then used as justification for not supporting a Shenmue 4.
I think there is a place for Shenmue, but in its present presentation it just isn't very marketable and that a remake or reboot could fix that, but it does come with ginormous risks.