If you're talking about an app that's a major part of your workflow for something, maybe this makes sense. But most of the apps that I've paid $2-$5 on are things that I'm only likely to fire up occasionally when I need them. Monthly fee to mark up photos or scan papers with the camera? I'll pass.
I honestly can't think of a single paid app that I use that I don't think is worth more than $2 to purchase forever. If there's an app I won't use often but professionals would use daily for years (say a house measurement app while I'm shipping for a house) I'm happy to pay .99 or 1.99 for the month or two that I'm using it, and simply unsubscribe when I no longer have a need for it. The real estate professionals that rely on the app however can pay that in perpetuity and get a better app out of the deal since it's actually making the developer money every month.
On the other hand, for an app I use every day (say Overcast) I'd be happy to pay a subscription price for monthly/quarterly/yearly use of it.
I think this will have 2 positive effects - 1) developers can be incented and paid for keeping their apps current and improved 2) the 'top paid' areas of the app store will be strongly indicative of quality, as the more people are willing to pay recurring costs for an app, the more likely it is to be good (games probably fall in a different category, but I don't do much gaming these days).
Subscription price is $5/month ($60/year) because it's a professional tool for sysadmins who use it all the time. Maybe you'd have paid $30 for it standalone, but now if you want to use it for 3 years, the price is 6x as high (and the software poofs when you stop paying).
The line between professional tools and software I'd like to use for totally noncommercial purposes once every couple of weeks isn't always clear cut, and the pricing policies on the App Store have tended to keep things at an affordable mid-range where I can buy something even if it's only for occasional use. Subscription prices seem to get priced for the heavy professional users.
The solution I'm hoping for (carrying on the VNC example) is a free tier locked to a single connection, cheap tier with 5 saved connections, and professional tier for heavy users. But you just know the net effect of this is going to be prices going up (they wouldn't be doing it otherwise), and there are frankly a lot of things that aren't worth a recurring payment to keep around.
I'll pay a subscription for an app that receives substantive updates. But most apps don't need that, and they don't provide them at a monthly rate (they may provide updates that frequently, but not pay-worthy updates).
The problem with subscriptions is that it's hard for me to justify paying a recurring $12/year subscription for an app that I'll use once in that time. These kinds of apps I'm most likely to just do without if they go to a subscription model.
It's a special folder.
When you put an app in the folder it will DELETE the app from your phone and store it like a symlink. When you try to open the app from the folder it will install it again for you.
Think of all the subscription money you will save!
Only $5 per month.