I suppose that one question that all this raises is whether any driver can come in and "Do a Hamilton" any more; let's face it, the world of F1 has changed no end since 2007. When Hamilton came in, there was almost endless testing - so Hamilton could get to grips with an F1 car. The tyres were changing from Michelin to Bridgestones - and this suited Hamilton down to the ground. Added to this, Alonso was a new driver in the McLaren team as well, so he didn't have the advantage of being the incumbent driver.
Can Magnussen come in and repeat this? Well, there isn't the level of testing available to prepare him for the drive, but there is a major change in designs, so this may advantage him, as despite Button being the incumbent driver, he may not have as much advantage as he would have done if the rules had remained constant.