For the purposes of buying something as intrinsic to a domestic market as a home, being in the local currency makes sense. Anyway, the dollar has been gaining ground against other currencies, and as other economies weaken there has been a flight to the dollar as a safe(r) bet. The main major threat to the dollar is Asian ownership of US debt, but that threat is more likely to come from geo-political strategic games, that will play out when resources become scarce. A similar thing happened during the Suez crisis, when the US threatened to pull the rug beneath the UK and France.
