I've spoken with the TF team and they've been clear that open-sourcing the lib was part of strategy to make Google Cloud more appealing. It was conceived as a lure, among other things.
There's a big difference between "TensorFlow is great, and Google Cloud is great, and you can bet your butt that TensorFlow will run well on GCE" than "Run TF and get locked in to GCE". In fact, as I read it, the selling point is actually much closer to:
"TensorFlow is great, GCE is great, the two work great together, and it's open source so you can trust that you _won't_ get locked in." In other words, no-lockin is a deliberate part of the value proposition of TF+GCE.
I'm gonna get in trouble saying this. But IMO OpenCL needs to die. IMO it's a half-baked open standard that's hard to use relative to CUDA. IMO what needs to happen is that AMD and Intel need to provide CUDA runtime (just say no to the driver API) API interfaces to their hardware.
Evidence: OpenGL is a wonderful open standard. But OpenGL happened after nearly a decade of evolution of closed IrisGL that ironed out a lot of weird quirks that infest OpenCL to this day.
I joined the CUDA team in March of 2006 (that's why I have 14 single-inventor CUDA patents, including one that is the basis of persistent RNNS by Baidu). IMO CUDA is a mature API. And CUDA needs to escape NVIDIA's vendor lock. AMD is attempting to make this happen with HIP and ROC.
IMO as CUDA team member #6, we need to help AMD with this effort. To that end, we need to let go of OpenCL: I'm sorry but it's a dead-end. And we need to get as much of the existing CUDA code out there running on AMD hardware as we can. And I hope (but I don't think they'll agree because reasons(tm)) that Intel will provide a CUDA runtime API to Xeon Phi (Knights Landing or better) because CUDA is a better API for parallel computation than any other existing contender at this point.
And that's my story and I'm sticking to it. But don't get me started on both Google and Apple refusing to expose OpenCL on mobile where it could have once made a real difference. That time has now passed. CUDA won, but we still don't have a CUDA or OpenCL interface on either Android or IOS.
"TensorFlow is great, GCE is great, the two work great together, and it's open source so you can trust that you _won't_ get locked in." In other words, no-lockin is a deliberate part of the value proposition of TF+GCE.