Senate Bill 100 for any that wish to read it.
http://www.leginfo.ca.gov/cgi-bin/po...or=johannessen
The bill states that the DMV is allowed to "provide an initial registration" on 500 qualifying vehicles a year under this program. Nowhere does it state any required period of time to complete the registration process. The registration process is left to the DMV. Currently, incomplete registrations can be renewed indefinitely with the payment of fees. And, nowhere does it state that the spirit of allocating a sequence number on a particular year is to have you complete the registration process that year. That too is left to the registration process.
According to Sacramento (spoke to them yesterday), once a registration has begun as part of the SB-100 program, the registration itself is the document to be concerned about. If your registration were to expire (due to non payment of fees, presumably), then there might be grounds to expire the SB-100 along with it...but even that would currently be a stretch to enforce; as the two (sb100 and registration) are not tightly coupled at this time.
So, currently, if you have ANY SB-100 sequence number allocated to you, it is valid and will be processed. It would be advisable to keep the incomplete registration on the vehicle in question current to avoid any possible DMV jurisdiction over the validity of the sb-100 allocation to that particular registration.
A DMV policy change and/or an amendment to SB-100 would have to occur to change any of this; and that won't happen overnight. Moreover, the DMV is primarly concerned with the collection of fees. They're paid whether the registration process is completed or not; so I doubt they care one way or another.