Old news. This has been discussed before. USA, England, Australia, France, Germany, even Spain and Sweden really developed the game of tennis. It makes sense that for most of tennis history they would have the best players and most successful programs because the tennis infrastructure was much more built up in these countries. Availability of courts, top-notch instructors/academies, wisdom/knowledge of former pros, professional tournaments, and of course funding all meant that juniors in these countries were more likely to turn into a top pro than those in developing/less tennis-friendly nations.
In the last 15-20 years or so it's not that the tennis infrastructure in these countries has deteriorated, but that it has significantly improved elsewhere. At least in the U.S. (not sure about Australia, UK, Sweden, and Germany), the tennis infrastructure has actually improved, especially with the rise of more academies and more structured junior competition. However, the tennis infrastructure has improved dramatically in places like eastern Europe and South America.
This is most likely due to increased political/economic stability. Is it really just a coincidence that Russian tennis became so powerful approximately 10-15 years after the fall of the Soviet Union? With the excecption of the ongoing Kosovo incident, which isn't nearly as severe as the events in the mid-90's (I'm not familiar at all with Serbian history so if I'm wrong just correct me), Serbia has been pretty stable for the past 10 years, which has allowed the tennis infrastructure to build up. Novak, Ivanovic, and Jankovic are around 20-22 years old. Is it surprising that they were around 10-12, the age when most players start training seriously in order to become a top player, when the events in Serbia ended? Economic conditions in Latin America have certainly improved in the last 20 years, and sure enough there are a ton of South Americans at the top of the game.
The tennis infrastructure is improving in Asia now, not so much as a result of increased political/economic stability, although China and India are certainly doing much better economically than they were 20 years ago, but rather because of more interest in the game. Look at the juniors, there are a ton of Asian players. We're gradually going to see more Asians in the top 100.
There is obviously a fixed number of players in the top 100, so it's natural that as these trends in which players not from the traditional powerhouse countries reach the top of the game it's going to be at the expense of players from those historically very tennis-successful countries.
To be honost, as an American and a fan of American tennis, I'm not particularly worried about any "decline" in American tennis. I'm pretty sure that there will always be a decent number of Americans in the top 100, with at least one top player. Sure, tournaments have been slowly leaving, but the creation of the US Open Series and the success of IW/Miami will limit future departures. The USOS has also increased TV viewership/attendance during the summer hardcourt season and therefore has increased sponsorship revenue. It's not surprising that ESPN has outbid USA Network for the rights to show the US Open. More viewership = more advertising revenue, and ESPN wants to tap into that. That extra revenue from sponsors, ticket sales, and the sale of TV rights all gets reinvested by the USTA back into the development of American tennis. I know the USOS doesn't gain much attention overseas, but in the US it's already been a big success and will become even more succesful in the future. That's why I'm not worried about American tennis. I'd be much more worried if I was a fan of German, Australian (although Tomic looks like he'll be the real deal), Swedish, and especially British tennis.
You make some good points. Right now there is a stunning gap betw the English-speaking countries who were formerly the major powers in world tennis and Europe/Sth Am. I can't help feeling that the the USUK and OZ have lost The WAY. You mention Bernard Tomic of Australia - born in GERMANY of CROATIAN parents, Tomic is a good example of a NON Australian making it good in tennis-poor Australia. Jelena Dokic is another example - born in Croatia of Serbian parents who were forced to emigrate during the Yugoslav civil war when Croatia ethnically cleansed all Serbs in 1995 (Operation Storm). Dokic was the leading Aussie women's player and rose to #4 in the WTA before the wrangling between her parents and the Aussie Tennis Assn destroyed her career.
You know that the British Tennis Assn tried to BUY Djokovic?! That's right - the Brits are so-oo desperate for a winner they offered Djokovic British citizenship and bigtime sponsorship in 2006 when he was rapidly moving up the ranks. Fortunately for Serbia Djokovic declined.
You mention that the decline of the USSR has brought many East Europeans more prosperity so they can have access to tennis courts. Actually the opposite is true. The Communists heavily subsidized sports and that whole program fell apart, many nations such as Belarus fell into DEEP poverty. For Yugo/Serbia the collapse of the old SU has been a CATASTROPHE.
Many times Ivanovic tells about how she had to practice in a drained SWIMMING POOL because that was all they had in Belgrade, there was no tennis center, no subsidizing of young juniors to go around Europe and play. It costs alot to do that. Many times the Serbs couldn't even GET OUT to play because of the extreme sanctions against Serbia. As Tipsarevic says `We came from MUD. No one helped us but our parents.'
IMO - the English speaking countries have lost The WAY. We need to think deeply about the directions our youth are taking. At my local high school we have 5 beautiful tennis courts. We often go there on weekends to play and 99% of the time the courts are EMPTY.