Others have pointed out in different discussions that the subscription model means you do not get to keep using the software after you stop paying for it. If Adobe raises the price in a year, two three years, you can decide without penalty to discontinue the arrangement. I have never heard of a penalty. Here's what Adobe's FAQs say in a section about this offer:
After the first 12 months, we will automatically renew your contract based on the current price of the offering which is not, I believe, saying it will go to $50/month, as that is not the "offer" extended here. So it seems to me you could eat the candy for a year, a year and a bit, and worst case go back to the state of affairs you have now. The software "calls home" occasionally and news coverage I read estimated that you would get about 60 days max further usage and one day the sw wouldn't boot.
There are some discussions/threads here about ways you might save out your work if you were afraid Adobe software would not read the edit list on your RAW. Others reading this please chime in if you believe this is not going to be possible, though, after making the jump to the subscription model.
I had planned to move to the original $10/month offer as I have the requisite [legal]PS installed (bought PS v6 at a very good price before the first $10 offer was announced to be sure I could do so). I had not upgraded LR when I heard about that earlier offer. NAPP people tell their membership that there are going to be several years gone by before THAT arrangement will change. (I have no solid link/reference for this, either). So I have a better fall back state than some. BUT as I have researched this post I do not see any references to the first offer to those who already had Photoshop CS3 and above. That offer was open until 12/31/2013. Would they be less willing to change THAT plan? More of a pro base? or does that imply they'd know we would be annoyed but then dial in the new cost structure for our business?
Last thought: all of these moves are for stockholder interests and the need to project revenues at particular levels to maintain that. Even if the original program was "successful" senior management might have said, "Get more money in the house before 31 December." We're customers and wallets. They aren't here to support (be nice to) our craft or small business. (I don't follow the stock and comments about its prospects...)