What I suggest is something several companies did, refresh an old game to give it a new life instead or in addition of a sequel. Sequels can be hit or miss. CS II is a miss, CS1 sells better and there's still no competition in the Sim City-like realm. So yes, a remastered version, kind of 1.5 would sell. I know I would buy it.
In 2023, PDX had sold 12 million copies of CS1 since 2015. I don't know how many bought CS II but probably no more than 2 millions were convinced to buy the sequel after 2 years and a lot regret it.
What I would like in remastered CS:
* No hard-coded limits (cims, nodes, vehicules etc.)
* More realistic graphics (if bought on catalog like CS II's, please change your supplier, at least for the cims)
* The CS II roads/tracks tools
* Seasons
* From the DLCs: tramways + Mass transit
* From the mods: 81 tiles standard (or even bigger maps as our PCs are more powerful) + TM

E, Find It & Move It.
* Mixed zoning
* some more things I probably forget
CS was done in 2 years by a 10 people team (7 or 8 when the project started, 11 at the release). A remastered CS wouldn't take 7 years and counting for the current team.
Adding code for everything but the kitchen sink isn't great design. We know the reasoning behind this: let's make a game modders can modify inside-out and let's sell DLCs for 10 years. So what great features are there, apart from those included at release (the seasons, the road tools, no hard-coded limits)? The most popular mods are exactly the same than in CS1 (but missing something similar to the 81 tiles mod). With everything you can modify in dev mode, you would think the modders would have already changed a lot of mechanics to satisfy a variety of players. But they mainly fix bugs and holes in the simulation. How long can you hope a game has potential?