I don't have an online source, but paper version of Business Week magazine did a graph on monetary value of each loophole for US Treasury, and carried interest impact was miniscule (remember that it's still taxed at 23.8% vs 39.6% if it was treated as income, and with so few people taking advantage of it, the total rake-in is rather small). Not that the loophole itself makes any sense.

If you want some major impact on government revenues (which would also open doors to things like public finance of campaigns, subsidized tuition, subsidized healthcare, etc.), remove the mortgage interest deduction and standard deduction, but then you quickly find out that one man's loopholes are another man's "Washington reaching into our pockets yet again".