Creating software has always been easier for SaaS type software than understanding the business and sales.
Do you think small businesses, e.g. the bodega on the corner, the local barber or nail shop have those concerns?
Don’t mistake a feature and a product - stolen and paraphrased from what Steve Jobs said about Dropbox. He was right, just premature.
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.