I had a Konica-Minolta Maxxum 5D, which had IBIS (a very early version). When it started to fail, it would lock the shutter so no shots could be taken. I'm sure current technology is much better, but IBIS can fail. ILIS can and does fail. Failures are rare. Moving the IS from the lens to the body makes the body more complicated but the lens less so. I would expect current IBIS to be at least as durable (and probably more so) than current IS in the lens. I think most of us upgrade bodies more often than lenses, so that should help offset the fact that the camera is used all the time (unless you actually use multiple bodies) and a lens is used only some of the time (for most of us).
7D Mark II, 50D, 17-55 2.8 IS, 100-400L IS, 10-22, Sigma 150-600 C, Sigma 150 2.8 Macro, EF-S 60MM f2.8 Macro, EF-S 18-55 IS, 28-135 IS, EF-S 55-250 IS STM, 580 EX II, Yongnuo YN-24EX, JasonC007 Diffuser Kit, Gitzo GT2531EX, ARCA-SWISS Z1, RRS B2 AS II clamp, Kirk L-bracket for 7DII, Kirk L-bracket for 50D