You're not alone
While I sincerely appreciate the effort TV has put into making their products modular, there is a limit to how far you can go, and I would not want TV to compromise on making the best unit possible due to backwards compatibility concerns.
I look at this like my computer: My PC is modular and I can upgrade my video card, CPU and RAM, but only for a few years. It's simply not reasonable to expect a manufacturer to still make upgrades for my old Pentium III... and honestly, why would I want to upgrade it at this point?
I feel like I've had a great run with my T1, Evo, Rev and DART. It's a solid modular system that I have enjoyed thoroughly. So long as the new system is modular in the same way the old system was (one base, many attachments), I'll be very happy.