ShivaVG is an open source alternative for path rendering. See this Stack Overflow question for a list of OpenVG implementations: Best OpenVG Implemenatation
Basically, you have a few options: use an OpenVG implementation (like ShivaVG), use an OpenGL implementation or extension (like the NV_path_rendering), or use something else entirely, like Direct2D.
However, other alternatives to NV_path_rendering cannot even come close to its feature set and the quality of its render. NV_path_rendering can natively handle fonts (which is a big deal—without fonts, you're toast), scale and so forth in true perspective (try that in Illustrator!), mix well with 3D, use sRGB, use fragment shaders, and does all this incredibly fast. It also implements user-interaction, which OpenVG does not specify AFAIK.
Uniquely, NV_path_rendering does not invent a new standard. Rather, it implements several industry standards, such as PostScript and SVG, with a focus on quality and speed (it's rare to have them both) that you cannot currently find anywhere else.
(Plus, Mark Kilgard is the project lead. C'mon. The guy's brilliant.)
Will it become standard? Hard to know. As for what to use, it really depends on your purpose/need at this point. Looking for quality path rendering for an app? NV_path_rendering for sure. Looking for basic resolution independent graphics in apps (esp. mobile)? OpenVG might be better. It's too bad that Nvidia's solution is not completely portable, but I wouldn't shy from using it. I'd prefer having a quality solution; sometimes portability isn't everything.
Nvidia has compared their solution to OpenVG and found that OpenVG doesn't provide too much benefit, unfortunately. So, yes, there might be hope for it to become a standard. But, since according to IBM everything in the future will be embedded, perhaps it would be better to hope for it to be open, instead of wanting more standards.
"The nice thing about standards is that you have so many to choose from." --
Computer Networks, 2nd ed., p. 254
For more info on NV_path_rendering features, I recommend looking at this: An Introduction to NV_path_rendering.
