Hi all, lots of good advices so far, and it's ok to be bias'ed as long as theres a reason. I will not comment on each post, but I see mainly 3 requirements I need to address.
Community momentum.
In the recent years Canon have unleashed a high number of different cameras, making it harder for us all to keep momentum. I guess names_are_hard nail'ed it down to D678X. Since most of development is taking place around D7,D8, this is where we as a comminity will gain the most. Also since I only have limited time to spend on the project it will be difficult for me to carry the D6 development on by shoulders. There are a many nice entry level camera with D4,D5, but the future is changing.
Trends
The digital single lens reflex era is comming in an end. Canon has still to release is last flagship(?), while others like 5D and 7D seires will be discontinued. The future is mirrorless, so from that perspective, I think it would be wise to choose a mirror less unit.
Personal ideas
It would be fun to have a fullframe camera for astrophotography, but most of the time (99%) will be spend in video mode where APS-C is just fine, and purchasing a lesser expensive unit would make it possible for me to get some additional stuff.
Canon M50 (D8) - might be a solution ?
Like some have mentioned in this thread, M50 might be the right one. Just look a ZEEKs videos, were he's squeezing every last drop of blood out of the ML build for the EOS-M's, looks great and fun, what a pleasure to watch. The Next camera line missing a ML is the M50, with the "crippled" 4K video mode and many other stupidities. Reminds me about .. never buy a Camera what implements a "new feature" for the very first time, because it's going to suck. Never the less, the M50 it looks really interessing. Wikipedia also states differences between the M50 and M50 MKII : "internal and external components are the same", which could make a future ML for M50 MKII a easy job. Also last but not least kitor did a speedrun on the M50, getting menu's up and running.