Given the range of scale of titles for the NGP (anywhere from $2.99 minis to $40-50 console level games), development costs are not going to be an issue for the platform.
Obviously, not every developer is going to have the desire or the resources to spend 1-2 years developing a NGP title. At the lower end of things, it should be easy enough to accomplish in 6 months or less with the resources of a small studio.
The two things that stand to potentially hurt development efforts for the platform would be ease of development (which prevented many developers from making early games on the PS3) and rampant piracy (which arguably reduced the number of titles being released for the PSP).
The first has already been addressed, with several developers already going on record as to how developer friendly the platform is.
The second remains to be seen pending the effectiveness of security measures that have been taken with the platform.
