From: Living in the fair city of Melbourne, Australia
I guess computing would roughly equal the current CO larger scenarios... As said, it would not be the whole eastern theatre or something, but rather those 100x300km perhaps at a largest.
But true there are games from other publishers, as HOI which you mentioned, that scratch this itch.
Dave, for one, has been thinking about this particular setting. You might or not know, that Dave made, a long time ago, in a galaxy far away, a boardgame covering the whole Eastern Front called Trial of Strength (look it up).
It is indeed possible, yet it would need a very significant bit of programming work, to make sure that everything makes sense at such a scale and decreasing fidelity in the models so the whole thing can be run on a desktop computer. Bil's requires substantial work, in the form of new features, rather than re-designing parts of the engine.
Re: larger scenarios. Paul Van Doren is working on something you might like quite a bit. It's totally like your favourite Bulge monster wargame - in terms of scale - yet playable, which is a big difference