None, they didn't supported his family when he was a little boy, they didn't supported his karting career, Formula Nissan career and Formula 3000 career, Alonso owe anything to Renault, the "moral debt" was payed a long time ago with 4 titles (WDC x2, WCC x2).
OK fair enough, I had a memory about that but I see it was Adrian Campos.
Anyway Lewis has repaid McLaren many times over for their outlay, it was only $4m or something, less than half a year's wages, or a couple of months at Ferrari.
Not that I agree with the OP at all, and I'm sure Hammy has no intention of leaving at this stage. This time next year, if the ~26 has been poor and maybe if Sebi is still going on about moving to Ferrari, we might have a real basis for speculating about a move when his contract runs out.