They probably blended into other clans until there was no more kinda like the native americans. Tsunade may very well be the last.
Oh yeah as far as the other half of the clan they probably died from the last 2 ninja wars.
There's got to be more than two living Uzumaki clansmen left in the ninja world.
Where are they hiding? Those waring days are over they should be grouped somewhere right? I mean they could be rebuilding there nation as we speak yo.