In a recently published interview on a Chinese site sspai.com (English translation available), mentioned in a tweet retweeted by @kcase.
Question by Waychane from ssai.com
More and more apps are taking subscription as their charge (paid) mode. Have you ever considered it? Can you share your opinion about subscription with us?
Answer by Omnigroup (bold added me)
We will be doing subscriptions, for the first time, very soon. We’ll offer a bundle where you can subscribe to all three editions of OmniFocus all at once: for Mac, iOS, and for the web. Since OmniFocus for the Web is an ongoing service, offering a subscription makes sense.
We will, however, continue to offer traditional licensing for the Mac and iOS editions, and some people will prefer that.
I was aware that the Web-version would be subscription based (see previous discussions, e.g. post by @Mischa). However, an option to also include the Mac and IOS version was news to me. Potentially interesting!