dland already has a 10+ gallon rig. Got to mention though, I found it takes about the same amount of time to brew 10 gallons as 5, which is why sold a very nice 5 gallon rig and set up the bigger one after just two batches when I started brewing again.
When I get too old to heave my keggles around I'll likely set up a more permanent brew space, (even indoor) and move to an even larger, permanently plumbed brew rig. Might do sooner if I score a nice jacketed 1 bbl conical.
I suspect from some of you peoples' posts some are drinking commercial beer on the side too, that'll cut down your need to brew even faster than decrepitude.