I think that RS will bring what DH did, a better version of the original. Let's be honest, DH had this over RO1 :
2 fronts mode
Catching in fire near tank explosion (last version of DH, freaking awesome)
Being hit in the foot = go prone
Revised penetration system for tanks
More realistic tanking in overall
Some maps were way bigger
Mobile respawns (maybe there was some in some custom RO1 maps, dunno)
New and better supression system
Player manned mortars
Way more tanks
1 more faction (Great Britain)
Rocket launchers
Smoke shells for tanks (don't remember having them in Original RO1)
More weapons
Scout vehicles (M8, Puma)
Better tracers (no laser beams

)
What else?