I purchased the last version of IntelliJ Idea and would upgrade if I see significant incentives in the product to do so. At the moment they seem to be throwing a lot of effort into releasing new products rather than working on existing products.
I can see an advantage for someone who wants the entire suite of products as long as new products are constantly added but not so much for someone who just wants Idea. With a subscription they have no incentive to make a product better as they have you hooked into using that product, if you want to keep using it you need to keep up the subscription.
Personally I can see myself going in other directions for what I want to do now that this has come in.