It'll work for a very long time. Browsers also still accept font tags and all that. Blink tags work. Marquee works. The align attribute works.
If you use the JS as posted above, those without JS will be able to open the link fine, just not in the new window. They can use the back button to go back. It's like the second most-used button on teh Interwebs.
Is there a special reason you need "target"? 99% of the time, links should be allowed to be links.