The spirit acquisition just expands B6's routing and economies of scale but it's not providing massively new destinations. AA still serve most of B6's destinations, and the smaller ones they don't serve are left to budget airlines like spirit/frontier. OW aren't really looking for small local airports, they're looking for connections from big cities to big cities. AA/BA have the majority of that covered. Additionally, the prime user of OW benefits for B6 flights is likely to be within the US. And where do pax within the US get OW status from? AA. Who has partnered with B6? AA. So as AA status pax already have reciprocal benefits on B6 and with them being the biggest user of those benefits I don't see that adding B6 to OW will provide a greater benefit to most people.

That isn't to say that it wouldnt be lovely for BAEC members to get benefits on B6, it would, but I just don't see it happening.