There is a trend towards the "subscription model". We've seen it with Adobe's suite of apps, Microsoft has done that with Office recently -- Office 365 subscription is access to the native apps during the subscription period as well as access to the online versions -- it has been around awhile.
The trend toward subscription model is generally misguided. When you buy software, you are pre-paying the whole amount upfront. Plus your chance of defecting to competitor in near future (aka subscriptio "churn") is almost zero. Plus when you get new product with new features out, customer has a good justification to repeat the whole cycle again.
Subscriptions are good for utility type services which are stable, has continuous consumption, has very low margins of profit and has much less competition.
Adobe's subscription model is dumb. They are purely thriving on consumer mindshare but these prices are going to start hurting. Adobe's core business is ripe for breaking in.
I think you are vastly underestimating how much effort would be required to create software with similar feature sets to what Adobe's has.
I gladly pay them $10 a month for Photoshop and Lightroom and photography for me is just a hobby, not my job. There are free and paid but lower-cost sorta-work-alikes to both of those apps (and I even use them sometimes -- RawTherapee in particularly has some nice features), but nothing I've tried free or otherwise comes close to the overall feature set in those two packages.
