As a web designer, I certainly hope not! I think this will help people find local businesses and as long as Google provides a link to the businesses website, it should work very well. There will still be room for business websites as you probably will only be able to store a finite amout of information with Google whereas you have have as many pages as you like with your own site (some small businesses I've worked with have had 000's of pages). A business website also has the added advantage of having enquiry forms and being easily updateable if you use a content management system.
If google could get rid of all those pesky websites and their annoying webmasters I'm sure it would. It's increasingly looking at ways of aggregating information from around the web and presenting it so that you never need to go any other website.