They'd have to approximate everything, and there'd be nowhere to start really. (At least on the aircraft named here). This is a study level sim, so unless the aircraft is fully or mostly declassified chances are slim it'll end up in DCS. Other common requests are the Super Hornet, the F-22, and the F-35. The Eurofighter is a rare exception, but the reason it's coming is that the developer has people close to the project that can help enough with the approximations to make it work. It won't be anything like the real world aircraft in how it functions, but will be able to get the job done "overall" and with performance that's vaguely similar. The only chance you'd have on an F-117, B-1 or B-2 would be if someone close to any of those projects was willing to do the same, which is doubtful. The F-35 would be more near likely since it's an international project much like the Eurofighter, but I wouldn't hold my breath.

Also, when it comes to the commonly requested long range, or record setting speed type aircraft - the world is just too small. For example, commonly requested aircraft are the SR-71 and the MiG-25. Also the B-52, and the aircraft you've named. The maps are just too small and the sim geared towards smaller scale things.

That said, players can already come together on those tasks easily. With dual cockpit functionality implemented and birds coming soon like the F-14A/B (D is still too classified to be worthwhile) requiring both a pilot and RIO, the F/A-18 (will be great fun on strikes or even SEAD), the Harrier, the aircraft already in game... There's a lot to do with multiple players.

You never know what will come, but aircraft that classified just aren't likely in the near future at all.