... But I'm not sure if I'm going to buy a Mac Pro again. My next main machine may just be a MacBook Pro ... as I am starting to need portability more and would be better off putting more money into a more powerful laptop than spreading my money between a desktop and a laptop.
I'm in the same mindset. There might be a lot of mobile usage in the future, but I love the dual processors of the Mac Pro. Might buy both in 2015. The MacPro is just a better experience than any of the other computers Apple has at this time, but they might do dual processor iMacs in a few years.
I'm also looking down the line at the iPads. Those will speed up; they will probably be quite fast in 3 or 4 years and then take over larger market due to larger application capability. They'll never be as fast as the larger portables until the processors and memory reduce far down and batteries can run fast iPads like MacBooks. Apple will most likely keep iPads as they are for 3 or 4 years, but the market will eventually force them to be more expandable and capable.