There are quite a few challenges for a developer to create the full experience of something like LR on an iOS device. For this reason I don't expect to see LR on the iPad imminently. Here are the challenges Adobe would face.
1. No colour management in iOS. Unlike on OS X there is no uniform ColorSync equivalent.
2. Lack of support for Adobe toolset/frameworks used to build LR on Mac (this is rather big as an issue).
3. Resource limitations. Although the iPad Pro looks like it will be very powerful, it will not have the RAM of a Mac or PC, not anything like it.
4. Different set of features required on mobile, the integrations with other things means an iOS LR would have a bunch of new features needed not in the OS X version.
These problems level the playing field for a potential competitor, but they would still face problems 1 and 3.
However a competitor can probably not afford to develop such an app, simply because they would need to charge $100-$200 a unit to get a profit. It would be a big investment with an unknown payback. Tablet sales are relatively small in the market and have tailed off.
It's hard to develop any cost effective professional app on iPad for an independent or small development house because the sales are relatively low and price point very low. Much better to target OS X where people expect to pay $50 for an app or even more.
That being said, I'm ordering an iPad Pro tomorrow with the keyboard and pencil to fully evaluate it. At the minimum I am creating an iPad Pro optimised version of my portfolio app.
I have to add that although I own several iPads and develop software for them I personally prefer to use a Moleskine style notebook for all my lab notes and design work. Maybe I can be convinced by the iPad Pro and pencil, but I prefer more traditional tools for creative work that isn't photo processing.
My gut feel is that handling large numbers of raw files will still be cumbersome on iPad Pro, but I live in hope and will test it for this purpose as soon as I get my hands on one.
I also have to put in a good word for Filterstorm which I haven't used much recently but this morning I used it and discovered that it has both curves and cloning capability.