This reminds me of the rollover penalties mentioned here;
https://bitcointalk.org/index.php?topic=1078521.0In any of these kinds of proposals there can be two effects; Either you penalize the larger blocks so much that it's never economically viable to actually make larger blocks (as is the case with the aforementioned rollover penalties) or you don't, in which case the nodes can make larger blocks to gain an advantage in the marketplace (Which is hardly distinguishable from raising the blocksize limit in some fashion.).
So if your protocol does the former thing, then it doesn't actually do anything in practice, if it does the latter thing then we can ask, "What's the advantage of this beyond the block size increases?"
1.) It destroys currency.
2.) It changes the block size cap to a block size target.
I don't see the advantages of either of those things, and at the end of the day we would still be periodically complaining about where the "target" should be, so down the road we'd still be dealing with pretty much the same problem except that it's been obfuscated by an additional layer.