I have several thoughts about this general topic, less about Jewell than about whether this is the start of a trend and whether it could affect UConn.
1. Regarding Jewell herself, her family situation (which I and probably everyone here knows nothing about) might or might not be a critical factor. When Epiphanny Prince skipped her senior year a few years ago, it was because her mother lived in a high-crime neighborhood and it was urgent for Piph to earn enough money to enable her mother to move out of there. I doubt if Jewell is in a comparable situation, but if there is some family illness or any other situation that requires or would benefit from a quick cash infusion, then that is certainly a valid reason for her to make this decision.
2. You have to be a REALLY good basketball player in the women's game for the WNBA plus winter income to be enough to offset the long-term economic advantage of a college degree. Jewell might be at or close to that level, but I doubt that many players are, so it is unlikely to become a trend.
3. Specific to UConn, I very much doubt that Kia Nurse in two years is going to be at a basketball skill level comparable to Jewell as of now. For her, as for Kalana Greene and others, taking a senior year in college (which is a pretty nice life with charter flights, plush resorts for Thanksgiving tournaments, etc.) makes a lot more sense.
4. Someone suggested that the risk of a career-ending injury while in college makes it irrational for any player to stay in college after she is eligible to turn pro. I would make two responses to that argument: (a) Most players who are going to have career-ending injuries have already had major injury problems by the time they are Jewell's age (e.g., Caroline Doty or Shea Ralph), and since Jewell hasn't had those problems, her risk of injury is low; and (b) the amount of money that a player can earn in a year or two before such a hypothetical injury is in most cases insufficient to offset the economic value of a college degree.
5. BUT, for someone like Morgan Tuck, who does have a history of injuries and therefore has an above-average risk of a career-ending injury, AND who will also have earned a degree by the end of next season, the calculation is different. If she looks like she will be a high pick in the WNBA draft and will command a significant foreign income, it may be perfectly sensible for her to pass up her last year of eligibility.
So I don't think that we have to worry about this becoming a major trend. But still, I hope for the sake of WCBB and interest in next year's season that Jewell reconsiders and returns to Notre Dame.