I think it would be great to have the possibility to use Budgie as a Tiling Window Manager. There are so many people who just like TWMs for how they work, and don’t want to lose their time configuring it along with xorg, the statusbar, notification daemon, app menu, etc. They just want it out of the box, like any other DE.
I’m not a developer, but I think it wouldn’t be very complicated to integrate i3 into an alternative Budgie session, since there is already a i3-gnome session and it doesn’t have much code in it: https://github.com/i3-gnome/i3-gnome
Other option could be to integrate Pop shell as an extension once is finished: https://github.com/pop-os/shell