1) BHA-2 - Maybe throw in some tech from the cubed series and fix the gain issues where you could have more volume play with the knob on all kinds of headphones...Furthermore, you could do a GS-X Mk2 type of thing with the BHA-2. The BHA-1 had great headphone amplification, but the preamp wasn't as good as the rest of the dedicated Bryston preamps. Maybe stepped control for preamps and remote control? Having an analog-only TOTL headphone amp and preamp in one box would be perfect. That's a product worth keeping for years/decade(s).
(I still use headphones occasionally nowadays, but it's been dramatically reduced so they are mostly for nights. I actually don't know how the headphone market looks right now in terms of both the headphone and amplification. The Audeze is the only one from the high-end headphone collection that I use now. Most of the time its the wireless earbuds and headphones))
2) Roon Core on BDP players - Either on the BDP-3 or a newer beefier processor model. Maybe we can get MPD type SQ from Roon this way? Also, an updated interface for Manic Moose / MPD would also be great.
3) As others have said, maybe something on the smaller, integrated side. For example, with my Amphion One15, I went with Amphion's Amp100, but the thought did go through my head that if there was something that was comparable to it from Bryston, I'd have preferred to stick with Bryston.