I have been using Adobe Photoshop professionally and I'm already looking at migrating away from Adobe products because of this.  There are a number of reasons for that.

One, I want software I own, not stuff I rent.  I'm a small business and I really prefer software that is mine and won't suddenly stop working if I don't pay whatever monthly fee they decide to charge.

Two, this would be at least twice as expensive for me as a small business.  Fact is I never got EVERY upgrade that came out.  Often I skipped one and sometimes two versions because they just didn't offer that much new that I needed.  Adobe software is expensive (right along with Autodesk).  This new "cloud" thing means I would be forced into every upgrade or I can't work at all.  Either you pay that fee every month as a constant ongoing expense or you're out of business.  Again, as a small business, that's making my livelihood at risk in a way I find VERY uncomfortable.

Three, I don't always even download the updates.  Updates to Flash have been notorious for bugs.  When I'm working on a project, I generally skip updates to any of my software, whether that be Windows, Adobe, etc.  Why, because I don't need a new bug introduced in one of their updates causing me to lose productivity.  I normally finish projects, then update (and allow a day to deal with any possible bugs) before I begin new projects.  With this, you'll likely be getting updates whether you want them or not.

Four, I'm not always connected to the internet.  GASP, shocking I know but sometimes I unplug the thing.  Oh wait, now my photoshop may stop working if it can't phone home.

Five, With all the increases in hacker attacks on businesses, some of which seem very coordinated, something that makes me even more dependent on the internet and possibly vulnerable to that stuff just seems dumb.  Right now my vulnerablity is mostly limited to scam emails (and I've been seeing more and more of that this past year).  What happens when those hackers decide to take Adobe servers down for a week... do I just go on vacation because my software stops working because their servers are down?

Six, who says they won't up those fees.  This gives Adobe pretty much all the cards.  They decide they want to buy another company jet or want revenue for their next big project... you suddenly go from $49.95 a month to $59.95 a month and there is nothing you can do about it. You either pay or you're stuck.  Oh, and will that lovely new Internet Tax the US Sentate just voted for apply to that price?  You might want to budget another 6% to 10% extra on that monthly charge depending on where you live.

On the other hand my old copy of CS5 cost me nothing to continue to use, never charges fees and works fine whether the internet is up, down or bent sideways.

So looks to me like Adobe just handed Corel a golden opportunity to recapture a slice of the market.