Let's be fair. Schumacher won 5 (I think) consecutive WDCs prior to 2005, and then he retired at the end of 2007. So that means aside from Alonso, we've lost 5 years when a driver potentially could have become champion and continued to race to the present day.
There are at least three potential near-future WDCs in the current ranks, so don't put down your bets just yet. Ten years from now you could look back to this day and count 8 WDCs.