Replacing old, wide-base, kitchen faucet - need base-plate for new standard faucet.?

Unless that sink and faucet combo have been around for more years than I care to think about, the porcelain finish under the chrome base plate shouldn't be rusted. It may be discolored slightly from crusted grease and soap, but that should clean off comparatively easily with some elbow grease and Ajax. I replace a lot of this faucets in my handiman business and have never seen one that was so bad that the customers wanted the sink replaced just to get rid of the sight of the old faucet footprint. Besides, even if it doesn't look the best, you pretty much answered your own question when you said you're planning on remodeling within the next year.