But in that case IBM can license the invention from you, which is also the idea of a patent. And instead of negotiating a selling price you would negotiate a licensing price.
Does that realistically make a difference? The only difference between selling it for $x or leasing it for $(x/3) (assuming GP's proposition to dramatically reduce the term), is whether they want exclusivity, whether they can back out of a lease early), and who shoulders the costs of defending it. At that point you've made little difference to how patents affect the industry, you've just increased the administration for the inventor.
But I'm certainly in favour of some use-it-or-lose-it clause that lets a "portfolio" age quickly.