there is no doubt Sony has a very serious intent.
However it will take a successful pro-spec camera For them to get amongst the big boys.
It is clear they are listening to what the enthusiast wants... but they have not really improved on the position the inherited from Minolta. it is not enough to have all your cameras in the mix, they must excel in one field or another to make a real mark.
That they dumped the excellent Minolta scanners did them no favours, it put them in a lower "Serious" category straight away.
The lens ranges certainly contain the required quality But perhaps not the required breadth to satisfy many professionals.

I would say they are serious but not contenders yet.