If you can be fast, and provide good images, it really doesn't matter what you use as a pro.
Today, some people might be a bit picky about grain in images. So to avoid that you can use a larger format (depending on the output size), and if you can process and scan it fast enough to compete with others, you can do it.
It's like in stock photography. Nobody cares how you shot it, as long as you give them a large clean file without digital or film artefacts of any kind. If you have direct contact with customers, add speed of work to that and you have a golden rule.
A professional wedding photog friend of mine shoots film exclusively. He uses a 35mm for photo journalit style stuff during the reception and uses a host of Hassy equipment for the more formal shots. He says that as long as he can still get film and decent, reliable processing, he'll stay with film. Interestingly, He says that he actually caters to a higher end of the market now - seems film based photos are recognised by some as superior and worth the extra time and money. It's all about marketing.