No they can't AmeriKiwi. Infact, the last salary cap increase which will be for next season has taken a lot of time to go through.
In terms of operations finances, only one club in the NRL consistently operates at a profit. The Brisbane Broncos. The Warriors themselves achieved profits in seasons 2001-2003. No other club in the NRL makes a profit. They get grants from the NRL from television rights, and most are propped up by a league's club - basically an organised casino.
In the past, we've seen teams like Manly Sea Eagles, Wests Tigers and South Sydney Rabbitohs have to play at below the level of the salary cap because they financially could not afford it. As such, with the salary's cap design to make it even for all clubs in term's of the rosters they can put together, plus keep club's financially viable, its debateable if it is in actual fact achievable to go further ahead as they will for next season.
"Won`t" seems like a better word than "can`t"... it`s certainly not impossible to do.
The problem is that the NSW Government is increasing taxes on league's club poker machine takings, which is significantly going to impact the amount of money they can provide to the football club's they represent.
The NRL, and the clubs, in my book can still look after player's interests without necessarily exploding the salary cap, through education schemes which gives a player a qualification to fall on once their career has finished. There is also of course the lure of Super League where a lot more money can be made for a player of significant quality.