Since the arrival of Scrypt asics, we're all aware ASIC's can be made for everything (not like I wasn't before lol). The only real way ATM to resist pure ASICs is to change/add algorithms continuously.
CPU miners are easily rewritten. GPU miners need a bit more of a dev, but christian shows it off pretty well!
FPGA miners, like Christian said, only need to add another FPGA, rewrite the code for the new/extra algorithm et voila. This needs a lot more development time, but I guess that someone who has been coding FPGA's for years will pull this off pretty easily (and if he's smart, not re-sell it!). FPGA's will be few and not really worth it if you can't rewrite it yourself.
And ASICs require hardware development at its finest. It takes a month, maybe two to get a working prototype and even that isn't what you'd call stable and ready to re-sell. So ASICs for X??? will never exist for the general market if it goes on like this.

THIS also makes it more or less "multipool-resistant" BTW. If the markets are filled with coins, each having their own algorithm, this will make it hard for a multipool to switch according to profit.
I wonder if it would be able to add something onto stratum that lets the stratum tell the miner which algo to pick, so it can change in an instant, without you requiring to manually do it?