Will potential clients/job pass over someone with no experience with film (both shooting and developing)?

Some might. Some might not. The exact answer is as varied as the number of potential clients/employers. In the case of contract work for clients, it might be as varied as each specific potential job.

You're more likely to be expected to have at least a rudimentary knowledge of darkroom processes and techniques if your potential client/employer still uses film as a photographic medium. If the photographer is expected to do the darkroom work themself, you'll almost certainly need a full portfolio of works you yourself have produced in a darkroom.

You're far less likely to be expected to know much about film if your potential client/employer works only in the realm of digital imaging.

The same is true of physical printing from digital image sources: If your potential client/employer uses physical prints, or even publishes using commercial printing processes, you'll be expected to have at least a rudimentary understanding of how all that works so that the images you provide will be appropriate to the medium in which your work will be presented to the public.

In the year 2018, an understanding of both commercial printing processes, such as those used to print magazines, and digital image distribution requirements are probably more important to most potential employers/corporate clients than anything to do with film and darkrooms.

Not to rain on your parade, but by the time a beginner today gains the skill, knowledge, and experience and has time to build an appropriate portfolio and a reputation at lesser publications in order to be considered by National Geographic, they'll probably be long bankrupt. So will most other print publications, at least as primarily a publisher of print publications.

That's not to say there might not be other entities distributing similar stories and images in the future. But it's highly doubtful it will be via a print magazine. The future seems to be moving in the direction of self produced works by individual photographers who build a small business (small, relative to what a large organization such as Nat Geo once was) around their own work. They market, publish, and find corporate sponsors themselves rather than working for a publishing company that does all of that for them.

The NatGeo thing is just a far out thing. I was more interested in about more realistic clients, such as weddings, local restaurants, etc.

For those types of clients, you'll need to understand about printing from a digital image far more than you will need to know about film and darkrooms. They don't care if you use digital, film, or a pinhole camera. They only care about what you deliver to them at the end of the process. It's up to you to decide on the medium that you use to deliver their images.

In theory you could say, "I'll only deliver digital images to my clients." In practice that doesn't usually work.

When you shoot a wedding and deliver only digital images to your client here's what usually happens:

• You shoot great images.
• You process and edit the images to look their best on a large, high quality, well calibrated electronic screen.
• You deliver the digital images to your client.
• They look at all of them on their 9" tablet. They don't look near as good on the tablet due to scaling errors, poor calibration, smaller size and resolution, etc.
• They choose a few to have printed. They select the printer based on local availability and lowest price.
• They use an app on their tablet to upload the images to the local printer's website for pickup later that day, not realizing that their app is highly compressing/downsizing the images to save bandwidth and time.
• The prints are produced at the local Walgreens by a high school kid who is more concerned with what is happening on the screen of their smart phone than what is happening on the screen of the minilab they're using to make your prints. The "automatic" correction settings of the minilab will almost certainly make your work look worse, rathrer than better, than your careful edits did.
• Your client gets their prints and is so unimpressed they don't even bother framing, much less displaying most of them.
• When their friends are planning a wedding they'll advise them, "I hired your name here because they were supposed to be so good, but the prints I got looked nothing like their sample images! I think the sample images weren't even theirs!"