All the kids where I live (an expat community) have a wonderfully enriched environment. Lots of very educated parents, many of whom have one stay-at-home parent with lots of time because of restrictions on employment here (and very cheap household help).
I've seen kids both "level out" from age 2 to 5 (i.e. stay advanced but lose the apparent advantage), and my own 5yo get further and further ahead.
Looking back, the difference is how quickly the child learns. A very bright child will learn something early if you repeat it often enough. The outliers learn it when you show them once.
Sounds like you have an outlier, but it's hard to really tell (I feel the same way about my 2yo honestly). About educational opportunities, I agree with polar bear about looking at a location more for the whole family and finding the best fit educationally. Not all gifted boys are ready for early entrance maturity wise, so it may not be a good option anyways. We're relocating in a year or two, and while good schooling for our clearly gifted 5yo is high on the list, family life ranks first.
