They will not support other focuser. ZWO want to sell their own product (EAF…) to people who already have an ASIAIR but doesn't own a focuser yet.
And for the ones who already own another brand’s focuser but are not willing to spend more money for the EAF, they’ll let you sell your ASIAIR on eBay as they are not loosing anything: that ASIAIR you sold stays on the market, it’s new owner may buy an EAF eventually.
Furthermore, make the ASIAIR supporting DSLR cameras is already very complex to them, so adding support for different focuser brands will generate more work, more bugs and unhappy customers in the end and this without any financial benefit.
The ASIAIR can be seeing as a “loss leader” : it’s make you enter an ecosystem, then you buy their other products …or die. The ASIAIR was not designed to generate growth for other companies ! Once you have an ASIAIR you can only use their products. And thanks to the attractive design, the simplicity (1,2,3 bla-bla) many lazy geeks (I’m one of them) will choose it over a more complex solution (a laptop with complex software programs). The amateur astrophotography market is still a niche, but it’s no more what it was 15-10 years ago: a very fragmented market: many small companies and very involved amateurs, some coding their own pieces of software... Even if this aspect still exist, the recent trend on astrophotography, new customers who want user-friendly products for a cheaper price (I’m one of them), influencers on YouTube and Instagram… all this changed the way companies like ZWO makes business. They tend to copy Apple’s business model and their closed ecosystem to generate more profit with fewer efforts. What we get in simplicity, we lose it in diversity and interoperability.
Lain