My understanding is Yes.
They will stay strong because Bing/Yahoo do not present real alternative.
It's the same user experience - Regular users can't differentiate between Google and Yahoo/Bing.
Being a leading alternative require offering different approach to the search experience. Some thoughts -
1. More related results.
2. 20-30 search results (but not zillions)
3. A news user interface to the web page result, including captured images, videos, products and eBooks etc etc.
4. Less ATF ads.
5. Page's section for research based content.
Why don't Bing/Yahoo, or any other SE, take up the challenge?