Not really. Many will switch registrations.
Define "many". Because we've seen plenty of open or modified primaries where you could walk into the polling place and either just take a ballot or re-register on site, but we've not seen many of the truly closed, must be registered a month before, can't change your registration at the door, etc. primaries this cycle.
Maryland's exit polls might be useful here.
Edit: 13% Independent, 3% Republican. Maryland was closed. (Some of the self-identified independents may be perennially registered as Democrats, others may have registered just for the primary. Obviously, the self-identified Republicans all re-registered.)
