Well actually I always had my strong doubts that the Crytek engine could or would ever be capable of modeling the same or similar amount of content as the ArmA/VBS engine does. Crytek engine seems IMO to be clearly designed and oriented to small map games (such as Crysis).
At best the Crytek engine could model a small scale tactical simulation similar to Ghost Recon 1 or SWAT4 with a few land and low speed vehicles such as tanks operating very closely to the players.
The "proof" of this is for example the new Chris Roberts space sim game (the "spiritual" sucessor of Wing Commander/Privateer) where the team lead by Chris Roberts is having a very hard time to model very large maps and this in a space simulator which naturaly have maps full of nothing (space or empty space). Now imagine in a simulation similar to VBS/ArmA where the maps are full of stuff!
IMO, the only engine that IMO could somehow compete and model similar capabilities as the VBS/ArmA engine is the Outerra
engine. Look here for more detail regarding the Outerra engine:http://www.outerra.com/
What's interesting about the Outerra is that it models the entire planet
and it also allows multiple platforms ranging from men/soldiers, to ground vehicles, air vehicles (helicopters and fixed-wing aircraft), etc... Of course one thing is the engine and it's theorical capabilities other thing is the real capabilities when you have a simulation with lots of units and players mixed in a multiplayer enviourment.
Apart from this I completly agree and understand what ebud says and I also agree that perhaps the best way to replace VBS with something better looking but with the same or better capabilities you'll probably need to develop something "from scratch" which of course would take LOTS OF MONEY!