If Venus and Serena can set aside other interests to make tennis their priority, albeit in the twilight of their careers, then that buys women's tennis in the United States some time to help the emergence of a new generation of tennis players.
Ball in Williams sisters' court to revive tennis in the US
When the Williams sisters burst on to the scene in the late 1990s, bringing style on top of considerable substance, women's tennis advocates in the United States had a vision, even an expectation: the talent pool would grow deeper and wider.
Venus and Serena would inspire black girls - especially those like themselves from a plastic fork, instead of a silver spoon, upbringing - to channel their athletic skills toward serving and volleying, not sprinting and jump-shooting.
As a bonus, white and Hispanic children from similarly non-affluent backgrounds would take notice, then aspire to become their own version of the siblings.
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And women's tennis in the country would live happily ever after.
As players, the Williams sisters have been transcendent. As Pied Pipers, well, they have double-faulted. No parade of prodigies formed behind them. Now the United States is paying the piper.
The dearth was painfully evident over the weekend when the Americans were humbled by Germany 5-0 in the Federation Cup.
Seventeen times a champion in the worldwide competition, they have been relegated for the first time from the cup's top-tier World Group, consisting of eight nations.
At first glance, injuries might seem a valid excuse. Venus is recovering from a sore hip that has idled her since the Australian Open.
Serena has been plagued by such an assortment of ailments dating back to last summer, from broken glass in her feet to a blood clot in her lungs. Bethanie Mattek-Sands, the world No 41, too, bowed out with a sore hip.
Upon further examination, the injuries disguise a disturbing reality, created in part by the sisters' occasional tendency to treat tennis as a moonlighting job. For the Fed Cup, the US would have suited up one Williams, at most. Neither has signed on since 2007.
Venus, a part-time college student, had shown interest in this year's event. Serena, on the other hand, could not care less about the Fed Cup, along with almost any other tournament outside the grand slam events.
The home page of her website offers clues to little sister's waning interest in her profession. Read all about her new pomegranate lip balm, along with her fashion savvy and acting chops.
As for Mattek-Sands, she would have been no imposing stand-in. In her stead, the US had to make do with teenagers Melanie Oudin, world No 81 entering the cup, and Christina McHale, who just broke into the top 100 at No 82.
Not surprisingly, they won not a set in four singles matches. Three cheers - well, one or two - for Vania King and Liezel Huber, who managed to take a set in their doubles drubbing. The Fed Cup fiasco confirmed, not revealed, that US distaff tennis has fallen on hard times.
At the recent Sony Ericsson Open, considered the unofficial fifth major on the Tour, the 96-member field found room for just seven Americans. The only one still alive after the second round was Varvara Lepchenko, a native of Uzbekistan.
Women's tennis is hardly the only activity involving sweat and scoring where America has yielded ground in recent years. The final leader board at the US Masters included just four home-grown golfers among the first 14 names.
Yet tennis is nowhere near the global game that golf is. While its participants' roots usually trace to the middle and upper classes, the Williams family demonstrated that a shortage of disposable income is no impenetrable barrier. There is no excuse for the decline.
The prevailing theory holds that the dominant tennis players, overwhelmingly Eastern European nowadays, are (a) hungrier, (b) tougher, (c) limited in sports options or (d) all of the above than the US. Mary Joe Fernandez, the US Fed Cup captain, discounts none of those.
Yet she said: "We're making progress. A lot of the younger generation is starting to make their move."
Indeed, several Americans are bunched in the low 100s in the WTA rankings. Good for them. But this is akin to climbing a mountain: reach a certain height and the altitude kicks in, making it difficult to ascend further.
The Williams sisters can help buy their homeland some time.
They can declare themselves all-in during the twilight years of their careers, setting aside other interests to make tennis their priority (even though you have to wonder about Serena's mindset when she announces a return to training last week with a Twitter picture of her in a hot pink body suit).
Then they can take an active role in recruiting the next wave of pony-tailed or dreadlocked players. ("Hey, you can get rich swinging a racket and still find time to design your own clothing line.")
The US Tennis Association approach, whatever it may be, is not working. The talent pool, rather than expanded, has shrunk to wading size. For the women, the past decade-plus has been a net loss.