What good is a .uk if you don't have the co.uk? if you try and build a brand on a .uk how much direct traffic do you think will be typing in co.uk? I don't want money bleeding over to someone else.
I wouldn't start a brand on .uk unless I had the co.uk to redirect.
Do you think most businesses will move to .uk from co.uk just to cut out the co? no, that will cost too much changing advertising and you will lose SEO value needlessly.
But will business have to register the .uk? yes to protect their brand.. paying a £20 tax.
Anyway you want to argue for .uk, there's an obvious reason why it wont work and shouldn't be introduced.