Yeah, that's not going to work. Let's examine the situation.

Almost 21 million bitcoins are already in the hands of people who agreed to the original inflation rate. They may even be the majority by the time it happens (hint: everyone posting in this thread will be dead by then).

Someone forks the chain to a new perpetual inflation rate.

The people who had coins prior to the fork now have coins in both chains. They don't want their coins devalued so they sell all their new fork coins and use the proceeds to purchase original coins. This has an obvious effect on the exchange rate of both coins.

The miners quickly realize that the transaction fees on the original Bitcoin are worth more than the block reward on the new fork. New fork is abandoned.

Now, this is just a guess, but it's based on the idea that the people already holding bitcoins won't voluntarily agree to having their coins devalued. I think that's a pretty safe assumption when they are given the option to choose. It's already been proven correct once, the block reward was cut in half and no one even bothered to try and make a "50 coin per block forever" fork, even though people loved to talk about it before the halving.

If a perpetually inflating coin is superior, one of the alt coins which already acts this way will take the market away from Bitcoin and we won't need a fork.

slaps self for responding to obvious troll