As an APL+Win distributor, I did get a number of requests for a 64-bits version of APL+Win.
I think customers do not realize all the consequences of this and all the things you'd have to do to create a full 64-bits version of APL+Win.
However their requests are there!
For me, the problems are probably similar to what happened when moving from a 16-bits version of APL to a 32-bits version (maybe more complex now though, of course, because APL+Win supports more things), which did happen and did happen very successfully. APL*PLUS PC evolved in APL*PLUS II which was immediately called "Zippy" because it could handle very large arrays so fast.
Yes, there are "millions" of ActiveX out there that can be used with 32-bits APL+Win, but there were "millions" [I exagerate] of 16-bits VBXs that could be used before ActiveX existed. And that did not prevent creating a 32-bits version of APL+Win.
Also, doing a 64-bits version of +Win does not mean giving up with the 32-bits version at all. It would just be an additional version for the people who need it, i.e. who need very large workspaces, for example. A possible approach could maybe be to do a 64-bits version of APL+Win very progressively over time, starting with the raw interpreter first, then later adding 64-bits ASMFNS functions, then later adding support for 64-bits DLLs, etc. And starting soon enough would kind of guarantee that APL+Win will still be there if one day 32-bits software no longer runs on Windows.