We'll see it start to do much now that the limit is actually being reached. In the process of syncing the block chain, the first three fourths of the blocks take up one third of the hard drive space; that means one fourth of all the blocks take up two thirds of the disk space. Thanks to the limit, these ratios will begin to even out.
You forget to say once the limit is reached, Bitcoin popularity (crypto market share) will start to decline pretty fast. Basically only limited transactions can be included in the block, if more transactions are required by users, some have never to be included. Basically it will be easier to use different coin than feeling the hours/days/never confirmed transactions pain with 1MB Bitcoin
