Here's my take on it: Supports are not co-dependent on the ADC, necessarily. They're more co-dependent on their team as a whole, as their team is co-dependent on their unique utility and talents to keep them alive in bad times.
Let me put it this way: to bring up some ancient League history, the ADC used to solo lane in mid, and the support was paired at bot with a bruiser, with the mage and the main tank going top. It wasn't until after jungling became a thing that ADCs were seen as too vulnerable to ganks when solo laning (with the most consistent ADC in that era being Ashe blowing her ult and both summoners to gtfo from a decent gank, and almost any other ADC just getting beat down) and they were moved bot lane with the support, whose new job was to not be a battery for the bruiser anymore, but to spam CV and wards all over the place to help track the enemy jungler, in addition to being their ADC's babysitter.
Also, there was at one point...
- The "roaming support" strategy that basically followed their jungler around and ganked lanes with him.
- The support/mage combination when Siege Mages (Ziggs, Xerath, Syndra, etc...) were a popular bot lane choice.
- The SUPPORT MID strategy, which was honestly a Korean cheese to get their assassin junglers fed through constantly ganking their lane.
Point being, they're not really limited to "bot with adc" and they really shouldn't be. That's not how diversity and evolution of gaming strategy works. As Riot is slowly starting to realize, trying to force a type of playstyle is the fastest way to kill a game.