BTW the only things left to them in my opinion are:
There are plenty of potential big products out there. That's not the problem. The problem for Apple is the law of big numbers. There are a relatively small number of products with enough market to move the needle once you are Apple's size.
Tough nut to crack like you said but I would have said the same thing about music a few years ago. I'd give Apple as good a chance as anyone. The market is big enough but it's unclear where the business opportunity lies. Lots of entrenched players and a byzantine market structure.
2.) Replacing the iPod Mini with a watch that syncs to your iPhone.
I think you are on the right track but the opportunity is bigger if you think of it more broadly. Think device and sensor integration. Right now devices do a rather poor job of talking to each other, even Apple devices. For instance I should have access to all my files, data, music, settings, preferences, video, address book, etc on each and every Apple device I own. It should be completely seamless. Right now it's still too spotty and device dependent. The market opportunity for that is huge for Apple and it keeps people in their ecosystem.
3.) Pull a M$ and try to merge there desktop class and tablet class together.
This is already happening to some degree and logically it makes some sense. I think MS did a hack job of it but they did establish that the concept is feasible. Apple has already started to make iOS and MacOS overlap and Google is doing the same thing with Android. It doesn't necessarily have to be a single code base but the code bases should work smoothly together if they can't be merged. Frankly I think laptops and tablets are going to converge much like PDAs and cell phones over the next few years. Right now they are separated due to the state of the art in technology but those barriers will disappear largely in a few years. Not sure how it will play out but it will be interesting to watch.
I presume you are thinking of something like Occulus. I've worked in my day job with immersive VR tech and I just don't see a big enough business opportunity there to get super excited if I were a company the size of Apple. Games has some market potential (overestimated I think but some) but what else? Most uses are pretty niche. However I do see a huge opportunity in augmented reality and geolocation which isn't all that far removed in a lot of ways.
Other potential big opportunities?
1) Automotive systems are a big opportunity and car companies aren't very good at the sorts of products Apple makes.
2) Payment systems are a huge opportunity. I could see smartphones making inroads into some of what we use credit cards for now.
3) Location based services - a lot of the money in smartphones is probably going to be here. Big fight with Google on the horizon here.
4) Buying other companies - Apple has a TON of cash. They could easily buy their way into markets.