The issue is that many times the company would LOSE existing revenue and that's often a non-starter during planning.
If your one-time price is $49.99, and their existing monthly fee is $19.99 per month, they're not going to offer a $49.99 option. It would harm their core business too much.
The point of the discussion for me (can't speak for you) was to ask if there's an opportunity, and I am not deterred to think there is.
Is it easy, no. But it's straight forward to approach from a product perspective.
There's strategies one may deploy to make it harder or more painful for a big company to copy because they'd have to swallow a large number of downsells into the new offering.
Maybe the insight from this thread, is that one must consider high-value low-product-effort features that, often, force upsells in the cloud solution that one could offer in an installable one.
Don’t mistake a feature and a product - stolen and paraphrased from what Steve Jobs said about Dropbox. He was right, just premature.