If by "in the future" you mean next year, then any new maps or upgrades will probably need to be purchased from TomTom, TomTom Home can be used to purchase and load maps, other voices (celebrity), updates to POI's etc.

I have tried the Western Europe map on an SD card (2Gig) and it worked great. I have read that up to 4Gig cards will work but 8Gig don't.