I don't know what ever happened to Netscape's version, but various homebrew attempts have been made.

One Linux on N64 project was discussed here a few years ago: https://news.ycombinator.com/item?id=25539319

There was a version of Mosaic in the SharkWire Online device, recently there have been some efforts to make that more usable without the SharkWire, though I don't think much is public yet, some discussion about the ROM here https://www.reddit.com/r/lostmedia/comments/1i2odym/update_f...