Yes, they should. And they are already very worried about it. Only know that with certainty about Shure but I'd be surprised if the other companies weren't thinking in the same direction.
My assumption is that we'll see the same development in the audio recording space as we saw it in the camera space. It's not 1:1 exactly the same - microphones have always been a lot more in the (semi-) professional area than cameras have been, and stage mics etc. aren't going anywhere. But for home recording, be that audio-only or the audio for your video, dedicated microphones (and audio interfaces) will see their market shrink significantly.
Guitar pedal and amp modelling of some real quality and portability hit the market over a decade ago, but in that time the boutique analogue market for effects and amplifiers has exploded.
It'll be hard to model the variations possible in microphone configuration. There are some techniques that will just plain require multiple dedicated microphones—no matter the environment.
But other solutions like Zoom handhelds will definitely diminish in number. I used to rent something like that to direct from the soundboard so a former band could record our live sets. Now all you need is a line-in to your phone.
Same with just being able to jot down ideas—I'm totally excited to have recordings to my phone not end up compressed garbled messes—even possibly usable? Yes please!
That said, if everyone is done with their Neumann's, you can kindly deposit them with me for free!
Again, very little knowledge about audio, but some knowledge about photography..
From what I have read, it is important to have a physically large condenser/diphragm for a mic to have high fidelity. Could you educate me a bit please?
At least for photography, I can tell you with certainty, an iphone camera is basically a toy when you are talking of challenging scenes being put on large fine art prints. It is nowhere near creating same "fidelity" images as even a micro 4/3rd camera, and there are medium format digital cameras out there.
You're absolutely right, and your photography analogy holds for audio, too.
However, if you look at the sales of consumer grade cameras as well as DSLRs, you'll see that smartphones ate a lot of their market. A quick Google gives you this continuously declining graph of DSLR sales, for example:
A phone will never replace a serious camera for large fine art prints. And the same is true for audio. But already, you have cases like Kanye claiming that 20% of the vocals from his last album were recorded in voice memos:
My assumption is that we'll see the same development in the audio recording space as we saw it in the camera space. It's not 1:1 exactly the same - microphones have always been a lot more in the (semi-) professional area than cameras have been, and stage mics etc. aren't going anywhere. But for home recording, be that audio-only or the audio for your video, dedicated microphones (and audio interfaces) will see their market shrink significantly.