With Sinar being integrated into the Leitz group, they can now offer solutions for all large sensor photography, but surely there is a gap that needs to be full filed to connect the two lines as they now exist, Sinar now only makes tethered backs (all MS capable) and only view cameras. Leica makes a large sensor integrated DSLR which can't have its back removed. The first move for integration was another version of Sinar's P2/P3/PDslr camera, that can take a Leica S (more than Canon or Nikon Dslrs) on its "rear standard" to be used instead of an MFDB. But surely this is a compromise for view camera users.
If one buys a Sinar MFDB there is no MF camera platform on either firms to use it on, OTOH leica's S-mount looks that has being designed having adapters in mind, where other MF camera users (Hasselblad-H & Contax 645 currently-more to be expected), can use their lenses fully integrated of their functioning on a Leica-S. I believe it makes sense if Leica (or Sinar), will come up with a new MF camera platform with interchangeable back capabilities, that would be able to take Sinarbacks on it and a new lens line to support it, that would (via an adapter) be able to be used on the Leica-S as well. It also makes sense if Sinar will come back to re-make self contained versions of their digital backs for that new platform (now they only do tethered) as they used to.
In the mean time, it's great news for Contax645 users, their system can play that same "role" to "bridge" the gap between Sinar and Leica, their lenses are fully compatible with Leica-S, and their MFDBs can be fitted on a Sinar view camera for work with movements… Heck! It even makes sense if Leica will invest to resurrect C645 instead of investing on a new platform now they have the adapter and Contax has a wide base of good lenses spread all over the world.