I see a lot of people on other forums saying it would be a guaranteed success—probably over 10 million—but the numbers from other versions don't seem to suggest that to me,furthermore, there are examples like FF7 and Metroid Prime 4 that show internet noise does not reflect sales.

So, tell me how well a Chrono Trigger remake would sell in two scenarios: 1 – A low-budget version: HD-2D, turn-based, like Live A Live.

2 – High investment and high risk for the best possible graphics: an action RPG, completely overhauled like FF7 Rebirth

Day-one release for PC, Xbox, Switch 2, and PS5.

If anything is written incorrectly, it's because I'm from Colombia and my English grammar is terrible.

Personally, I don't see not much more potential than with a Dragon Quest or 2D FFVII remake. Turn-/Strategy-based JRPGs just aren't big in NA nor EU, unlike other genres e.g. platformers (Crash and Spyro remakes as a shining example). It would be a sure-fire blockbuster success in JP, but outerside of this one region, a Chrono Trigger remake would struggle to find an audience.

Much bigger than what you would expect.

Better than LIVEALIVE remake in sales. Worse than a FF6 HD2D Remake. HD2D is the only way I see it being remade. A full 3D is just too costly for today's industry. PS2 era was the perfect time to remake it in 3D. I remember that fan remake that looked toughly PS2 quality graphics about 15 years ago. They got a cease and desist.

3D is not that expensive if you keep the scope of the maps small and the routes short and avoid the hyper-realistic models to everything. Original CT reuses several of its maps and only touch some details and colors to represent the passage of time. I think it's totally realistic to expect it as a budgeted 3D game. For the overworld they can go to Expedition 33/Dragon Quest VII strategy, this way they can cut the costs and speed development. The original game put all the fight into the dungeons anyway, no need to a big and detailed overworld 

I’d like an HD-2D remake. That idea interests me more than a 3D remake.

However, I’ll take anything I can get. I’m missing that game on modern platforms. But, my ultimate preference would be a proper pixel remaster of the original SNES game and story without the PSX/DS additions (I find that stuff a bit tacky).

EDIT

Sorry, I didn't even answer the question (because I read down the thread). I will now: I think the 10 million potential would only be possible across years and with numerous platform releases: iOS, Google, Steam, Switch 1/2, PS4/5, and so on. And this only after numerous sales. But at the launch price, I think we're limited to 3 million or fewer. The market is significantly larger than it used to be, but I wouldn't say the number of people who buy top priced games has grown at all; and arguably shrunk when you consider 100 USD today has an exchange rate of 45 1996 USD. SNES games in 1996 cost 55 USD or almost 120 USD today. So, I'd say the majority of sales would come at a lower sales number, not the launch retail price, which means 3 to 5 years before it reaches numbers like 10 million. But I'd agree the potential is there with the size of the market and the reputation + quality of the game (IMO, Chrono Trigger remains Square's best crafted game, even though my overall favourite is Xenogears).

Probably not great without significant marketing. The original one wasn't even released in Europe, so it's not like it's not all that well known. I mean, it has a certain reputation for sure, but it's probably not all that well known. I can see a remake making sense financially, but at the same time the realities need to be taken carefully into account.

I can't speak for others, but it would be a day one purchase for me no matter the route they go with it, and there are few games that are day one purchases for me.