Assuming the new brand makes quality pieces, they could make watches exactly like the originals, or nearly the same but with modern materials or new dials colors and new movements. For example, a speedmaster with a 3861 or a heritage navitimer or a new Ed White.
If the price is at or below a comparable vintage piece, people might say why buy vintage when I can get new?
There could also be people who don't know the brand and decide to seek out a vintage watch after seeing the reintroduction.
My sense of the new Ed White is that it slowed the vintage EW market, even though the entire vintage market was also slowed recently after inflation was targeted.
There's always a market for nice condition vintage. Poorer examples generally have fewer buyers when a person can now buy a new example. But even excellent examples of vintage may take longer to find a buyer after a new release.
I could be 100% wrong. Consider this perspective as coming from a typical watch guy in the middle of the herd.