there is a very good chance that as 64 bit architecture becomes more prevalent bridging may become more difficult. Continuing to use 32 bit plugs will get trickier as time progresses!
This is not groundless paranoia. It could happen. But I don't expect it to happen very soon. Whatever plugins you now have will likely be considered obsolete long before they become un-runnable. And that includes all your current 64-bit plugins.
Consider the history, specifically the timeline of 16-, 32- and 64-bit architectures, operating systems and applications. Windows came along in the early 80's, running 16-bit applications on 16-bit Windows. 16-bit programs continued to be supported right up to 64-bit Windows 7. That's a period of 30 years - the equivalent of a geological epoch in software time. The install base for 32-bit applications is thousands of times larger than the 16-bit base, making it even harder for Microsoft to engineer 32-bit apps out of existence. I expect to be dead and buried before 32-bit software can no longer be run.