Firefox will require users to install an extension in order to add search engines instead of just visiting websites.
And developers will have to create extensions that barely anyone knows about let alone bother to install.
Much worse than today's solution of including a little code in your website and have users autodiscover your search engine:
<?xml version="1.0" encoding="UTF-8"?> <OpenSearchDescription xmlns="a9...spec"> <ShortName>Website Title</ShortName> <Description>Search my website</Description> <Url type="application/rss+xml" template="mysite.com/search?q={searchTerms}"/> </OpenSearchDescription>