No doubt Apple has a roadmap laid out for the next few years in terms of features, when to add them, software updates to focus on, etc.
They're a company that puts profit first. Not a bad thing since this means they have to do stuff that entices us to buy or keep upgrading.
Marketing driven updates is here to stay. I've no doubt they sit on some updates so as to make a big splash later with one. Apple loves promoting big numbers or 100's of new features.
Should be pretty obvious Apple is looking at multitasking, notifications, quicker SMS replies, changing settings on the fly, home screen changes, themes, better screens, how to achieve hd recording, etc. The constraints are plenty though as they have to balance this with maintaining a very user friendly UI (this is key), app compatibility, at least one past generation phone compatibility (or making sure the most recent phone can support upgrades), etc.
If you jailbreak, you've already seen how some of this stuff could be done.