But yeah when bigger devs do this it's to show publishers that the title has market interest beyond just market data and sales projections.
A title like this is so niche that no one is willing to fully gamble. On it which is why he's been trying to get a third game for years,now he can.
Not to mention that the original outline or plan was to make at least 12 episodes or so.
Shenmue is a "beloved" game in North America and perhaps European region because most of the people who actually bought it and played it to "enjoy" it ignoring reviews ended up buying the game years after as used pre-owned copies.
The few of us who actually bought the game new at retail and weren't scared of by reviewers negative jabs or bad comparisons to GTA3 and actually kept the game are very few. Meanwhile a good unknown number of gamers were participating in then buying practices encouraged by then EBX and Babbages that you could buy and finish a new retail game, then return it and buy something else...causing the big stores to not order as much and getting full profit from selling pre-owned.
Meanwhile SEGA Japan used Shenmue elements to make Ryu Go Gotoku aka Yakuza series which started on PS2, when localized got predictable comparison to GTA series. Later the Yakuza series got on PS3 where they surpassed Shenmue elements in gameplay and graphics over time and was fairly successful sales wise in Japan while North America region largely sold mediocre leading to less localized sequels.
No surprise why Shenmue is niche and why there is absolutely no logical reason to actually believe old DC fanboys, that making or remaking the game would be profitable in an age where if Call of Duty, GTA, or some major title ends up blocking the sales potential of a game...not to mention buying practices still encouraged.
The devs want to do it but there's no trust in flaky consumers.
They're such old games that it really shouldn't cost that much to port them to PS4/XO... but they may no feel that its a viable expense until AFTER Shenmue 3 proves to be very profitable. This is reinforced by how scarred SEGA was by the low profits on those two
If you google, you'll find useful tools for this, there is one that is more recently updated than the rest. Even with that one, scaling to 1080p seems to work fine (albeit stretched from 4:3), but the actual rendering resolution causes the game to slow down hard if it goes above 4:3 960p w/FXAA.
You just proved why "porting" Shenmue to current gen consoles is not cost effective.
Shenmue started out on Sega Saturn and became a DC game limited to 4:3 aspect ratio meaning the entire 3d polygon graphics engine and art assets would have to be dropped in favor of a new 3d engine and new versions of art style assets along with new stuff or use Yakuza's latest version of 3d engine as a base.
Higher resolution, either 30 or 60 fps and 16:9 aspect ratio is going to expose a lot of ugly old textures that looked great back then. Hence they have to and need heavy funding not just talent which they already have.