If you make the necessary changes to fix it, it'll make FR fans mad
I really don't think so. Very few FR fans care much for Zakhara; the most typical FR-fan viewpoint, in my experience, is that it was the best of the cultural knock-offs attached to the setting, damning with faint praise. And well, FR fans have already had many real-life years to absorb that there's been two metaphysical shakeups and 120 in-game years since we last saw Zakhara. The relatively rarer Al-Qadim fans, in my experience, would largely have no objections to a thoroughly revised version; most are far more attached to the idea of Arabian Nights fantasy than to the specifics of the particular implementation.
Those things go even further for Maztica and Kara-Tur; strong fans were rarer, they were even more fans of the underlying concept than the actual implementation, and FR has even more built-in reasons for those places to have substantially transformed since we last saw them in product (Shou Lung was conquered by the Horde last time we saw it in any major product, and Maztica was shunted to another world before snapping back). Of all the pitfalls involved in revisions to those areas of the Realms, old fans being angry are not really an issue.
The major advantage I could see in revising them rather than just doing new settings from the same cultural background is specifically to purge their problematic elements, so that issues with the old implementations can be answered by WotC with a "Yeah, we fixed that."
But this is all getting far afield from the question of what products WotC is going to make in 2023 and 2024, since I doubt any of FR's Cultural Expylands will be the 2023 classic setting or the 2024 revisit.