That's why I support the idea of getting rid of the Proof-of-Work mining altogether and replacing it with Proof-of-Stake. Right now miners are parasites to the network. The only owners of the network are actual bitcoin holders.
Satoshi's invention of mining (which probably should have been called "confirming") not only secures the blockchain but has one very important side-effect: the disbursement of the 21 million coins into as many hands as possible, i.e. distributing BTC wealth. This job is 2/3rds complete.
Would we prefer it if 73 people who happened to be around in the first months of 2009 got all the BTC to begin with?
Satoshi's PoW was very good for the initial distribution of coins but only for that. I don't support 100% PoS coins at all, that's the reason I hate NextCoin for example because 100% PoS is corrupt and unfair distribution. However, a hybrid between PoW and Pos (such as Peercoin) is the best approach. You have the coin slowly transforming from PoW to PoS over time. To put it into the context of Bitcoin, now would be the time when we should start seeing PoS blocks around and perhaps over the next 4 years PoS mining should become dominant to PoW mining.
A hybrid PoW/PoS mining model gives us the best from the both sides. It's the fairest initial coin distribution and energy efficient in the long term. As a bonus it makes network development decisions much easier to have a PoS coin because in PoS mining the miners and coin holders are the same people, so they can use their private keys to their stash to vote democratically what protocol changes to implement and what not.
Actually, I think that your suggestion is what is needed eventually, perhaps when the block reward gets below < 1BTC.
There is a long-term threat to the PoW model when the reward gets very small, "re-mining", where miners deliberately ignore recent blocks en-masse in order to grab the transaction fees for themselves. The incentive structure dissipates. However, IBLT should help a lot in this situation as it gives non-mining nodes some influence over the miners to only take tx from the mempools instead of orphaning. Might not be enough of a force and a PoS element could help.
Microsoft supports Bitcoin XT! 
Always a good idea to observe where the smart money is headed.