It might work out that way, or it might not. The current open-source community is very much a product of current social conditions, and those conditions might change. They've changed before, and could change again.
Things like LLMs and the xz backdoor, for example, may make it unappealing to accept code from people you don't know personally; things like Apple's notarization requirements may make it impractical to run open-source software except as part of a proprietary package; software patents or legal liability for third parties using your software could make it legally unappealing to free your code; etc.
But another perspective for win32 support in future metal is the bigger "community" (users, software, etc) so the increase in support complexity is compensated for much (much) larger incentives for supporting much more diverse and desired old software. WINE and related SW is a testament to this