Hi Yakov;
Yes, with the demise of Distributed PB, EAServer and the PB Application Server plug-in - the n-tier support for NVUO's in the middle tier has been whittled down to either PB.Net of PB Classic NVUO's deployed to IIs. You are correct though in that it looks like PB.Net EOL'ed when Appeon takes over PB as I have not seen it mentioned anywhere specifically in their PB webinars. If I were Appeon I would not be putting any resources behind PB.Net as: its based on the outdated VS2010 shell; has <5% adoption rate; WPF direction in the MS world is not longer key; cannot produce Console, Service, Winform, etc applications; no support for current .Net features; slow, stability issues; etc, etc.
It looks promising that Appeon will address the middle application server layer for business logic as in their high-level PB Roadmap they did target NVUO support and adding WCF support into PB Classic. I am sure the Appeon will do justice to the NVUO support in their application server with detail to performance and database caching (which is already in their architecture).
What I can depart to you based on building some very complex Appeon Web & Mobile production applications is its amazing performance. It automatically deploys DataWindow's to its Server and manages the data demands from the Web or Mobile client using its AJAX technology. Not only does Appeon effectively manage the data caching and round trip accessing & updates it also compresses and encrypts the data-stream which is important for Protected "B" applications with sensitive data. We have built some amazing applications with Appeon at my government client, including implementing business logic in the middle tier using PB Classic Web Service based NVUO's.
What we have been doing is extending the functionality of PB & Appeon via web service implementations where the need functionality was not natively available in that Appeon Web or Mobile or we need to encapsulate sensitive data processing due to Protected "B" requirements.
Given Appeon's direction, past performance, commitment to delivery, current PB road-map, etc - I definitely think that they will address the middle tier processing area. I also get the impression that they want to assist the current EAServer developers in moving over to Appeon technology. For that to happen, the commitment to a robust middle tier like the features EAS already provides would seem to be a key direction in their 5 year plan.
What I would suggest is that you download Appeon Web and Appeon Mobile and get some hands-on experience with their products, rich mobile features, architecture, etc - then participate in the new planned open forum enhancement program to help Appeon shape their software direction for the features that you mention above.
Regards ... Chris