According to someone I know that works at Comcast, they're working on rolling out symmetrical (or at least closer to symmetrical) speeds—even over coax—within the next few years. I'm able to get 2000/200, which is decent. Metronet just buried fiber in my front yard, though, so I'm looking forward to symmetrical fiber soonish (though Metronet has been building so fast I'm worried about growing pains).
Yes, there's actually a significant ongoing scandal over this because they're only rolling it out (in most cases) to people renting their expensive hardware, even if the modem you bought already has the necessary DOCSIS 3.1 support. It's so scummy.
Unfortunately, though, there are currently only three customer-owned modems approved for higher upload speeds: the CODA and CODA 56 from Hitron and the CM2050V from Netgear. The first two are from a company noone has heard of, and the last one is $350 (!) and includes pointless phone support. None of the near hundred other DOCSIS 3.1 modems on the market are supported, for no apparent reason.
I can understand it to an extent—easier to do an initial roll-out when you're able to more easily control the parameters—but it certainly isn't a good look.
What's more scummy (IMHO) is that it's actually cheaper for me to rent their modem—which includes unlimited data—than it is for me to pay the fee to remove the data cap.