Absoltuely not nothing!
If you have Canadian GC, at least the Visa is multiple entries till I-94 expires.
Besides, once GC becomes citizen, you can travel to US, looking for jobs, or go to schools without any visa.
More important, no worry about out of status, you can always come to Canada temporarily if you are a GC holder, or just stay in US without worry about losing jobs if you are Canadian citizen.