Eh, with his comments and struggles last season I could see him taking a pay cut, closer to 5M (maybe even down to 4.5M if we're lucky).
Marleau's contract came after two straight 25+ goal seasons, and before that regular 60+ point performances. Toronto also seems to overpay on many of their signings.
Kovalchuk probably had somewhat of a bidding war, and he was regarded as one of the best players not in the NHL upon his return. He seems to be living up to that hype.
Joe Thornton had been the face of the franchise for San Jose for a decade - they were gonna pay him whatever he wanted.
It's difficult to speculate about until we have a better idea of his performance this season. I don't think Spezza sniffs 7M again in his career though, unless he leaves and a team is really desperate for a top 6 center.