As other comments have said, the effects on congestion are controversial [0][1].

> which in turn means a decline in the use of public transit

Not necessarily. If a trip would not have occurred otherwise, then there would be no decline in public transit utilization (subway lines seem to be closing with increased frequency recently, and people may have no other means of returning home). Of course, this would point to increased congestion.

> the big tax on cars was an 18% tax on parking in NYC, but considering that more and more people are taking Ubers instead of driving themselves

Would eliminating street parking further this policy? On many streets, it would allow for 1-2 additional lanes to be created.

[0] https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2838043

[1] http://www.schallerconsult.com/rideservices/automobility.pdf