Just a quick thought, what if engineers construct/repair the forward spawn and soldiers plant c4 on it?
Forward spawns.
Which forward spawns? 
This could also cause problems with the balance then, as the planting would take just too long. Not to mention, that the soldier is on his own while planting and the engi can construct with the help of more players.
But I’m not sure what you mean with “forward spawns”. Do you mean the capturable one on Waterloo?
I was also thinking about this since seeing Inferno’s post about side objectives. In the stopwatch version of goldrush there was a cp that is constructed would provide a forward spawn closer to the gold. It could then be destroyed by a covert ops satchel charge.
I liked it since if attackers managed to construct it, it could provide the boost needed to win the match. On the other side it was a nice variation from just watching the courtyard all the time. (defence)
After seeing these posts I really realize how linear db’s maps are atm. There is no way to skip objectives or trickjump over a wall or even do a side objective.
Maps needs forward spawns, they’re a key mechanic that’s sadly missing at the moment, but they need to be capture-able by either side, they need to be strategic (i.e. actually benefit the team that has it) and they need to be able to change hands quickly, like flags in ET rather than stand next to something for friggin’ ages like Waterloo.
But this is an aspect of map design, it’s difficult to see where they could put meaningful forward spawns on the current maps.
all true, the forward spawns are bringing something dynamic to the game/maps and needs thinking instead of shooting and linear walking the same path/objective over and over again.
But again i think its already to late to implament this as they said they arent making huge changes, so lets hope they read it and keep it in mind.