Struggling BlackBerry's 26 percent gain this year from depressed levels won't last, Mark McKechnie, wireless equipment analyst at Evercore Partners, told CNBC's "Squawk Box" on Tuesday.

In fact, McKechnie said he thinks the stock will be just about cut in half to $8 a share by year's end as the company's new BB10 smartphones come with a changed business model on top of strong competition from new Google Android devices and Apple iPhones.