But Not So!!! ... says Rodney Pimintel, Deputy Director for Capital Projects at the SFCTA. The as-yet-unbuilt Central Subway WILL connect to the existing subway lines on Market, come hell or high water; it just depends on how you define "connect." Via email, he informed us that you might not be able to hop off of one line and then onto another; some of the plans involve a pedestrian tunnel connecting Powel to as-yet-unbuilt stations near the Moscone or Union Station. Those as-yet-unbuilt tunnels would provide subterranean retail access, like the Nordstom's hellmouth in the Powell station. So, it would be exactly like getting off of one train, walking a few blocks to the next (as-yet-unbuilt) station, and then getting on another train, only without having to ever go above ground and see the light of day. Or like a shopping mall with electrified third rails.
So anyway ... that's good news. Sure is a lot of "as-yet-unbuilt"s, though. Yep ... suuuuuure is a lot.