Might I suggest a generic "100 years from now", but keep the range, so if the map maker is from 1915, the year the map is in in 2015, etc. I like the idea, but think restricting all maps to 2010 would be a bad move.
Maybe - I was trying to keep it from getting too science fictional, but I suppose the 2010 of someone in 1930 would be pretty wild anyway. Or we could have a range: 25 to 100 years, say.
Bruce