All depends on how you plan to get that first job. If you already have a company lined up, are planning on joining a startup, or are using the alumni network at your university, you should be fine. But, if you're going through your university's placement office or planning to resume-apply, the lack of a full major will really hurt your job chances.
If it was free, definitely stay and do it. You will learn the most interesting things in that last year, particularly if you fill your CS electives by volunteering to work on a professor's research project.
It sounds like you are going to do so anyway, but strongly consider asking the scholarship provider for an extension. If you have a reason, many of them have a relatively simple form and approval process (at least, the corporate one I'm most familiar with -- MSFT's 4-year full ride had basically a rubber-stamp extension).
If it was free, definitely stay and do it. You will learn the most interesting things in that last year, particularly if you fill your CS electives by volunteering to work on a professor's research project.
It sounds like you are going to do so anyway, but strongly consider asking the scholarship provider for an extension. If you have a reason, many of them have a relatively simple form and approval process (at least, the corporate one I'm most familiar with -- MSFT's 4-year full ride had basically a rubber-stamp extension).