The only real problem I see with this is if Intel charges a fee to unlock on chip functions, it essentially means those functions MUST be enabled once unlocked (no chip binning).
When a chip is sold as a 3 core that *can* be unlocked to enable the 4th core, it's not guaranteed that the 4th core will actually be functional. It's a gamble.
When a chip sold at X frequency is overclocked, there's no guarantee as to what speed a given sample can actually be overclocked to. Everyone who OCs know that each sample is different. It's a bit like a lottery with some winners and some losers.
Regardless, unless there's a significant performance difference in unlocking on chip functions, I don't see the typical consumer paying the "upgrade" fee. $50 will actually provide a pretty significant difference in performance when buying CPUs as most builder know.
But, as it's been mentioned, having this type of pricing does potentially mean that OEM companies can offer lower starting prices for pre-built systems. And that's good of course.