Steelbeasts is a good sim, but as said the graphics engine is over 10 years old. It can be bettered in a number of areas I think, not least in modelling close air and artillery support which is abstracted. That and their Challenger2 is something of a bad joke.
Something LIKE steelbeasts in DCS would get my money though, but as said, what lets DCS down in this regard is the lack of terrain. Trees can be driven through, and whilst from 5000 feet the world looks great, what lets it down is the lack of hull down features or other terrain.
It may well we would have to put up with the latter just to make sure the flight sim component would have decent frame rates. If so, well fair enough, but it would definately bring combined arms alive. At the moment it feels more an exercise in moving counters around than any real vehicles.
If anyone is serious about doing a tank dcs, contact me. Ive a number of manuals of British and Soviet tanks. The latter not surprisingly are in russian, but some of the diagrams will doubtless be useful.