Of course! They have to have something to tantalize us with.
I am gathering at this point that nobody is having the grad brushes in Lightroom 5.6, whether they're getting it from the cloud as part of their subscription, or otherwise..
Unless I hear otherwise, I'll assume that is correct.
You're correct. I believe that they're not introducing any major new features in dot releases of LR because, unlike the latest version of PS, it's still also available as a perpetual licence: start putting new features into LR5 and nobody on a perpetual licence will feel the need to purchase an upgrade to LR 6. LR is torn between the two camps (subscription and perpetual licence) and it seems that compromises are being made.
(I'm also looking forward to seeing those new grad brushes in LR when they finally happen.)