Once you buy it stays there, nobody can re-buy it. To reply to Vod, I'll keep site as long as I can, depends on number of sold bits. Minimum 5 years, if it takes of, minimum 10 years. I'll add that to FAQ as well
That is why these sites fail. You promise minimum of five years, but you register the domain for one year.
You won't spend money to renew the domain if you're not actively making money.