The proposal I'm putting forward is a simple one--consolidate the 17 and 33 into a single new route, eliminating the current Market East jog both take in favor of connections offered to the Market Street buses at Market and JFK. This route would run service at a 15-minute headway and would be, like the 2, 7, 23, 47, 57, and C buses (and Broad Street Line and Philadelphia2050's proposed Loop Network) part of a frequent service core in the, er, urban core.
Consolidating this service would still allow for connections to other core frequent services at Cecil B. Moore (3), Girard (15), Spring Garden (43), Market/JFK (10, 11, 13, 34, 36, and the MFL), Chestnut/Walnut (21, 42), and Lombard/South (40)--as well as possible frequent service route modifications along Race/Arch (31, 48) and Spruce/Pine (12, 30), and expanded light rail service along Girard (37 proposal) and Washington (49, 64) (see here). The bus sections of this proposal can be implemented with relatively minimal cost: putting out a new schedule and map, and putting up new bus station signs; the buses (and drivers) taken off the now-defunct 33 would go to augment some of the more poorly bused routes in this network (mostly east-west).
Sometime in the near future I'm thinking of showing a map of this (unwieldy-named) Core Frequent Bus Network and connections, in the contexts of both current, and suggested Philadelphia2050, operations.