I agree with Fishrrman that this will be the likely sceneario, based on past Apple history with the end of PPC support.
It is possible, though I feel it's very very unlikely, that Apple will collect them for you during update and move them to a "unsupported" folder. Microsoft has done that in the past with "antique" apps that were known to cause problems, but doesn't do it as a general rule.
I feel the best approach is to leave apps in place, possibly tagging their icons as Apple did with the unsupported PPC apps, and disabling, but not deleting, any auto-start apps, drivers, and services that are no longer compatible.