Null transactions require mining. The question is if nobody wants to mine who will mine? Old mining chips are already so cheap they cost less than a cheap bitcoin transaction. It would not cost much to mine just to preserve the value of your holdings.
The point of submitting the transaction would be to incentivize mining by posting a bounty for it, in the form of a transaction fee. It would be just like paying other people to mine at a loss on your behalf.
