While it's nice to have generalist search engines, it would be even better to be able to unbundle the generalist search engines completely. Verticals such as the following would be nice:
1) Everything linux, unix and both
2) Everything open-source
3) Only news & current events
4) Popular culture globally and by country
5) Politics globally and by country
6) Everything software engineering
7) Everything hardware engineering
8) Everything maker community
9) Everything financial markets
10) Everything medicine / health (sans obvious quackery)
11) etc.
Maybe make a tool that allows the community to create the subset creation recipes that perform the parsing out of data of a certain type and that the community forks and improves over time.
The time to create a generalist search engine has sailed, but specialist search engines is total greenfield.