My front tooth is turning dark - could I get a crown on just the one dark tooth and see results? (photos)

My front tooth is turning dark from a dental trauma and root canal. It's been internally bleached multiple times but still turns dark because it was knocked out a few years ago. #9 and #10 both have root canals. My dentist thinks I should crown them both and veneer the two on the other side. I don't want to commit to altering four teeth to fix one. I'd like to just crown the one dark tooth but am hoping it's possible to achieve good results and for it to look natural. What is recommended?