I do know I would like to stay close to business portraits, fashion, products, and maybe some weddings (low-light ability for not being able to use flash is key) areas of photography. I like shooting with natural light but I do have a Canon EX550 (I know I have Sony but it was free so I use it manually with a converter). I also have a set of flashpoint studio strobes.
Based on those, I'd say your best bet is getting into the flash/strobe game more. Business, fashion, and product photography get infinitely harder if you are relying on natural light; I can't even imagine business and product photography without controlling your light.
In fact, with flash and strobes, you could get by with a 60D for quite some time (I shot an entire wedding with one and never felt lacking with flash). And then when your jobs pay you enough, you can get the 6D and have the 60D as a backup. It makes your intitial lens selection tough though; buying the EF-S lens limits you when you get the 60D. Might be wiser to get a Tamron 17-50 non-VC for cheap ($300ish), get a prime or two, and have those options for full-frame. Focal lengths will depend on what you usually shoot, but the 85mm f/1.8 or 100mm f/2 are good longer primes. They'd work even better with the 6D.
Another camera you missed would be a 5D classic. Probably get it for about the same price as the 60D, and you'd gain a bit of low-light coverage.
But, it is probably smarter, right now, to keep your Sony gear, rent a lens for the wedding, and just be able to jumpy fully into the 6D. Going APS-C before full-frame when you know you want full-frame will end with you wasting money. And it's not like the A65 is incapable of taking good pictures