There is a lot of serious talk that the next version of Windows will be subscription based. Microsoft is in a unique position to do that, since its customers have no alternative but to accept whatever MS decrees if they want to have access to most of the useful software in the world.
The advantage to the developer is a steady income stream. He can predict how many employees he will be able to afford without waiting to see how many customers will buy the new version. If business is slow he can fire some support staff and slow down the bug fixes...er I mean additional features. If people stop paying the rent, he can decide he needs to make a change quickly before everything is lost.
The purported advantage to the user is that he can get instantly released feature updates. That can be done without the subscription model, the developer just has to release updates as soon as they are ready regardless of how the user is being billed.
The disadvantage to the user is that it will almost certainly cost him more on a prorated per month basis than the current purchase model--especially since software typically has a long useful life if you are not interested in new features. Word 2000 still works very well and does everything that most users use as well as anything newer, and I did not retire my last Windows 2000 computer until last year. And of course, it presupposes that the user will also have a regular income, and be willing and able to spend a cost effective amount of time using the software on a regular basis.
For a professional shop making a good profit using Sonar, a regular debit from the credit card would be nothing to worry about. For a hobbyist who does not touch the DAW for weeks at a time, it is unlikely that the model could be made to work, unless some kind of micropayment for a couple of hours of authorized use could be worked out. For a small number of casual users the lower cost of entry in a short rental period could be appealing (think of a paid full featured demo version), but how many of them will be around in a year?