No. The switch accounts feature has always been there, this is new with plus pages.
You still click on "switch accounts" to switch between channels/pages, yes, but you don't have multiple accounts, you only have one account with multiple pages. Once you transferred the channel to a page you don't get to access it directly from the account anymore, only if you act as the page and once you transfer the page ownership to another account the old account doesn't have access anymore at all. (Unless you make it a manager, cause the other way around you can also have multiple accounts lock into an manage one single channel, without giving your password away.)
