Jagex ultimately decides what will be updated and what not. So, they can make skillcapes F2P, but not other high level P2P content. In case that happened, the bonuses on capes of achievement could be nerfed. Paying 5 bucks for a pixeled cape, whose use is to merely earn "recognition" and "respect" from other players, is a horrible investment, in my opinion. Most pure F2pers would get P2P in order to enjoy the full game at full throttle. That's why making skillcapes F2P is a more reasonable suggestion than making all members' skills, weapons, armour, minigames, boss monsters and areas F2P.