Removing Xen from the name had nothing directly to do with changing the model for Xen Server; all Citrix products were re-branded at the same time.
You never know what corporations will do with products they're supporting, whether they're open-source or not. (Ask VMWare customers how they're feeling now, for instance.) But with open-source, if there's a large enough user base, someone can step in and take over the software to fill the gap -- and in fact, that's exactly what's happened with XenServer: the XCP-ng forked the open-source part of XenServer, and now Vates (the company behind XCP-ng) is actively collaborating with Citrix on future development. Removing features from "free XenServer" wouldn't really have that big of an impact on customers, since they'd almost certainly end up in XCP-ng anyway.
You never know what corporations will do with products they're supporting, whether they're open-source or not. (Ask VMWare customers how they're feeling now, for instance.) But with open-source, if there's a large enough user base, someone can step in and take over the software to fill the gap -- and in fact, that's exactly what's happened with XenServer: the XCP-ng forked the open-source part of XenServer, and now Vates (the company behind XCP-ng) is actively collaborating with Citrix on future development. Removing features from "free XenServer" wouldn't really have that big of an impact on customers, since they'd almost certainly end up in XCP-ng anyway.