How about Google is forced to split up into two competing general search engines? Google is a monopoly, little different from Bell in the 1970s. Bell was forced to split into two corporations due to anti-trust laws: https://en.wikipedia.org/wiki/Breakup_of_the_Bell_System
Bing is so relatively tiny that its existence hardly matters. If Microsoft can't compete effectively against Google, then who can?
Edited to add: Perhaps the main problem is that Google has access to waaaaay more data than anybody else. They know what everyone is searching for. They know which search results get clicked on. The data that you would need to have any hope of building a better search engine is all owned by Google, so there is no real hope of competing with them.
Microsoft has access to information on what you do on your PC to feed into Bing. It's not a data quantity gap. And Bing has overlapping results for a lot of queries.
If you mean "relatively tiny" in terms of traffic, how do you know that's not just brand recognition at this point---Google still thought of as a "search engine company," MS as "an OS and business software company dabbling in search?"
The Bells were broken up because another telco can't compete in a market where lines are already physically run. This is not the case for search.