I'm a little confused by this. My former employer hired some foreign citizens periodically and it's true that getting the right kind of visa is treacherous and time-consuming (especially after 9/11), but the employer as an institution was the sponsor. Wouldn't SFB be the sponsor for the right kind of visa to work in the U.S.? Is there a new requirement that they also now find an individual to "sponsor" them for visa purposes?
I can't imagine that this type of 'sponsoring' is actually related to visa sponsoring, which is a complicated process that involves the employer. Actually, are we sure that all three dancers are non-US citizens?
In any case, since so many dancers in the US are from other countries, I would imagine that it's just chance that the three dancers in this case happen to be.
Of course I was referring to financial 'sponsorship' in this case. Tan now lives with her parents in the Bay Area, and I don't know if her father was able to get work in this country, so it has to be expensive for the Tan family to remain here each year.
I can't see it being coincidental that Kochetkova, Tan and Karapetyan are being helped in this manner - they are arguably the biggest draws for the company. Whether Karapetyan has gotten dual citizenship is a question (now that he is married to Zahorian). I would expect Tiit Helimets to get a sponsor as well, but I'm not sure of his citizenship standing (assuming that has anything to do with it).
I really just think that the SF patrons are trying to help make SFB a rewarding place to be for these dancers, so they are less likely to leave the nest.
We don't know how the financial arrangements work at SFB (at least from what I've read here), but from that old NY Times article, it seems that it would be unusual for the sponsorship to consist of extra compensation over and above the salary paid by the company. I saw this mainly as a way to shore up company budgets by recruiting donors to pay some or all of that dancer's salary/benefits, although perhaps that's not always the way it works. Major donors like to have their names on things (buildings, theater chairs, classrooms, etc., etc.) and get recognition, so sponsoring dancers fits right in with that incentive.
The comparison with endowed professorships at Universities would not necessarily be helpful here. At some schools, the named endowment is buying a supplemental salary, research account, reduced teaching load, etc. in combination with the base university-paid salary. At others, the revenue from the endowment pays the full salary and perks of the professor who occupies the chair. So those professors with endowed chairs are getting extras one way or another but (as someone noted with endowed "chairs" in orchestras), the endowment stays with the institution and a succession of professors occupies the chair over time.
Finances are difficult for many U.S. dancers, not just those who are foreign-born, especially corps members. We had a link a few weeks ago, as I remember, to stories about how young dancers survive -- waiting on table, sharing apartments with several other dancers, teaching, etc., etc.