It will take no more than a few months for the whole "new gtld" thing to blow over. As soon as companies realise they can't push uphill against the billions of pounds spent each year advertising .co.uk extensions (and, globally, the tens or hundreds of billions of pounds spent advertising .com) they'll back off.
Even if a couple of hundred "top" extensions succeed because the companies behind them are household names (e.g. Google, Coke, Microsoft, Pepsi, Sony, Facebook, Twitter, Hilton, etc. etc.) this will have ZERO impact on the wider takeup amongst the general business population.
Remember, it's US$180,000 just for the application, plus probably 2x that to actually set up all the legal/technical/business structures to reg a gtld. So it's only going to be the top 0.1% of companies that would even CONSIDER doing so. The average small-to-midsize company is as likely to apply for a gtld as to send out its products wrapped in solid gold leaf - never going to happen!
So I for one literally can't wait - that giant flushing sound a few months after the gtld launch, crash-and-burn, will be the wiping away of all remaining doubts about the supremacy of .co.uk and .com as the ONLY game in town. And at that point the domain aftermarket should switch rapidly from first gear to top.