With CI+ it wont be possible, as both devices are going to be paired and you aren't going to be able to pair the CAM with anything else that has been approved. Of course it might be hacked in few next years, but as you know there are already few non-hacked copy protection schemes used in DVB so only future will tell if it is possible or not to use HTPC to receive channels that have been encrypted with CI+.I'm not shure what will happen but i think a lot of htpc users would not like to miss their features and so they will start to do illegal things with CAMS / Softcams and stuff like that - but it is forced by the providers.Especially the DRM lock down that is looming in the future could be a killing strike. It might end the pay channels for open source based HTPCs completely.
My cable company has already taken the nice step towards dancing with the movie / content provider companies. In their great wisdom they have decided to start to use CAM pairing with SD channels as well (which is not even required by the content providers, as only the "premium" HD content should be protected). This will render CAM + PC combination useless as no PC is going to be found on the approved settop box list. Sad, but nothing we can do about. Similar lockdown is most likely going to start happening with the DVB-S side as well.
And as you know such illegal activities aren't allowed to be talked on MediaPortal forums, so please no discussion on that topic anymore or the posts will be deleted without a warning.