I agree with Tool Agnostic. You don't need to upgrade everything at once, or even at all. Focus on what needs to be upgraded most, but plan ahead.
Upgrading your dust collection system is a good start, but it doesn't necessarily have to start with a new dust collector. Deal with your distribution first, but plan for making it compatible with a newer collector for the future.
If you have wall access now, run some electrical circuits for future use. You don't need a ton of circuits in a 1-man shop, but you will want a lot of outlets, because many of them will be obstructed or in the wrong place. Too many people get carried away with the number of separate circuits, but for a 1-man shop, virtually all of your convenience outlets can be on 1 or 2 circuits. Even for dedicated tool circuits, you generally cannot operate more than one stationary tool at the same time. Dust collector, compressor, and tablesaw are the main exceptions.
Keep in mind that wire-wise, there is no difference between a 120 and 240 volt circuit. So you can still wire a tool circuit for 120 volts now, and change it over to 240 later.
I didn't see a compressor in your list, but you might want to consider a heavy 5hp compressor. Not only will this be handy for woodworking, but you might find yourself acquiring some pneumatic mechanic's tools, such as impact or ratchet. Furthermore, if you've never operated a Dynabrade ROS sander, it will blow your mind with the difference from ANY electric sander. (I own several Festool sanders that were given to me, but I don't touch them, because nothing compares to a Dynabrade.)
You're right to consider a track saw. My tablesaw and sliding table attachment wouldn't even fit in your garage, at 110 square feet, but I find myself reaching for the tracksaw more often than the tablesaw these days. One doesn't replace the other, but I would have killed to have a track saw back when I was a professional cabinetmaker.
Because you have a tablesaw, I would recommend the Festool TS55 as opposed to the larger TS75. Get several track sizes. I actually use the short ones (32") pretty frequently, but also have 55" and 109" (plus a few others).
Pardon my shameless plug:
One of the most valuable tools in my main (basement) workshop is my Festool ASA5000 overhead boom arm. It's too big for the average woodworker, and costs a ridiculous amount of money. So a few months ago I started to produce/sell my own smaller version of the Festool ASA5000 boom arm, called Prometheus
. It allows you to have dust collection, electricity, compressed air, or anything else you want, anywhere in your workshop. Even though I don't do woodworking up in my garage, I mounted a Prometheus boom arm up there just so I could have pneumatics, electric, and vacuum power overhead without tripping over cords.
I took the Festool design, and improved it. Theirs weighs 300 pounds--mine weighs 30 pounds. Theirs requires massive structural support--mine does not. Theirs costs $5000--mine is around $1500. Prometheus is available in 6, 8, and 10 foot lengths, with free shipping in the continental U.S.. (Just in case anyone was wondering, I am a former
Festool consulting engineer.)
Prometheus can be ordered at: http://www.rts-engineering.com/