Re: USA or AUSTRALIA. Who will be a stronger force on the tour in 5 years time?
Probably the US.
In 5 years time Stosur will be 30. I think Dokic and Gajdosova have the best games to do well in Grand Slams and big events, but I don't really see Moore, Ferguson, Rodionova or any of the other girls getting there and being major prospects.
The US always seems to have prospects who step up when desperately needed, which is what it will be when Venus and Serena retire unless someone comes along before they do both retire. Coco Vandeweghe seems to have a big future especially. But ultimately, the US has more depth than Australia does in WTA players, so there's a much higher chance of someone breaking through and saving the US rather than Australia.
It will be interesting to see, because you never know who just might come along.