I really, really wouldn't bet on the next model coming with integrated wireless of any kind (maybe BT, but even that's stretching it). The japanese market just has too many options for cross-country wireless, each with its own adapter.
Honestly, my next PDA will probably be some kind of Treo, because knowing Sharp, they wouldn't be able to build a PDA-phone and make it decently usable. Until I loaded Cacko on my 860, a *lot* of things were broken.
The PDA itself is very, very powerful, but the Sharp apps are braindead compared to a Sidekick 2 or a Treo (especially in the level of integration). I might consider an MDA IV if the software is decent by the time it's actually available, but its use of non-standard protocols everywhere is not really encouraging.
The KDEPIM suite of apps is much better, but the integration is also insufficient. I'm trying to help Zautrix fiix that, but there's only so much 2 guys can do.
</rant>