I don't think RDS really cares about SHLX. It's such a small size. I mean they will do the drops of course, and over time sell down their LP stake for sure, but I don't think they are going to really grow the business strategically. They will unload it, maybe to KMI, after all the drops are done. And once the market thinks the growth isn't there anymore, they price will drop.
I don't think so either, but there is a lot of institutional demand from all these new funds in the MLP sector.
The only positive though is that you don't know what can happen. They can add quite of a bit of these "equity options" in pipes and plants b/c of their sponsors size. Plus AR can be bought out and the acquirer may have assets of their own they would drop down to AM. With Warburg Pincus owning such a large part of AR and the GP of AM (which is not the same thing by the way if you see a chart of AM ownership structure), you really never know what could happen.
I suppose I would put it this way, don't short AM.