He never said the problem was all so big right now. But do you suppose we just think about today and don't give a shit about what happens in the future?
ovidiusoft, you have rised some valid points for further contemplation. (And got a bit too much childish critique for it instead of a mature discussion from some members if you ask me.)
First of all, I sort of agree with your assumption that the whole network is going to stay whole for such a long time as 10 or even moreso 100 blocks. There will not be transactions that "will not propagate enough".
Because if there will be, this basically means that the network is split, and some serious shit is going on. In that case we will not have to worry about some transaction not being included, we will have to worry about a 100 block long reorg, which will make the recent mtgox hack seem like a fart in a hurricane.
So while this would be most probably technically possible, it is till too early to force an inclusion of a transaction by the network, it seems like it creates more problems than it solves.
Instead I am more for just increasing the fees with time. And the more I think about it, the more it seems that fees should be percentage-based with some minimum limits to still prevent spamming of small transactions. But even that is a bit too early, because it will only solve a real issue when the block reward will decrease and transactions will have to become bigger in order to pay for all those 5770s and keep the bitcoin's contribution to global worming on the level.
For an actual change right now, what somebody else suggested here about a way for a transaction to expire after a certain block number if it has not been included seems reasonable. That way if your transaction doesn't get included, you could resend it with higher fees and not look like a backstabbing double-spending sonofabitch.