As this is not a compulsory tool in our organization, I would say all depends on the decision makers, however since this is a part of MS Office, I am sure we will have it for as long as we will possibly need it. However, I would not be so sure, if it was a separate product.
I bought the standalone license, not the Office 365 Business subscription. This allows me to share the application with other users on my computer. OneNote has proven to be a valuable tool in a very short time.
If you are only interested in using OneNote, without using other MS Office products, then I would recommend using Evernote instead. OneNote does, however, come as part of Office Home and Student, which includes the three base products, Word, Excel, and PowerPoint. Those products are useful for students as well as most office employees, and getting the package may be worth the price.
I think OneNote is great at what it does. I like what MS has done with it and how they worked it into the product stack as they have. I feel confident that more great things will come in the future though I am quite content with this important application as it is today.