It is possible to make permutating algorithms for FPGAs rendering ASICs pointless.

Like this thread stated earlier, FPGAs and GPUs are not driven by the bitcoin related market.
This means that for each new process node (28nm, 14nm etc) the generic hardware is available to all and prices are not influenced by bitcoin mining.

For the ASIC market to function properly there would have to be a lot of competition to drive down margins.
They must also make enough money to follow the advancements of the silicon industry at all times.
Currently bitcoin is nowhere near the size needed to support this.
This fact makes it much easier/cheaper for irrational players to attack the network compared with a system where ASICs didn't have any advantage.

With the current algo bitcoin really needs ASICs to protect itself.
If there is a 51% attack,  I think algorithm changes are inevitable.