It is a sign. The end of dSLR's and the rise of the mirror-less. The end is near.
It's really not.
Firstly, as some people may remember, the original 7D was set as "discontinued" four months before the announcement of the 7DmkIII; the 24-105 f/4L was set as "discontinued" 18 months before the 24-105 mkII was announced. A product being listed as "discontinued", even with no replacement directly in sight, does not automatically mean the end of anything.
Secondly, when it comes to the 7D series, mirrorless is not yet in a position to replace it. The Sony
α9 and Fujifilm X-T3 have gotten the speed in place, but they still fall behind in durability and battery life. The 7D, 1D, D8xx, D5xx, and Dx series of bodies by Canon and Nikon will have a purpose for existing as long as it takes for mirrorless to catch up in battery life and durability. That the current fast mirrorless cameras also only achieve their speeds with various combinations of rolling shutter, lower resolution/further cropping, and/or generally compromising on IQ is another factor.
Third and finally, SLR as a whole still has about ~5 more years left in it. It's still what the factories are all geared up to crank out;l that alone will mean entry-level systems will stick to SLR designs. Just as the switch from film to digital was not overnight, the switch from SLR to mirrorless will also take a few more years. (Remember, digital photography first entered the market in the early 90s...)
Realistically, the next 5 years will be a transition period as mirrorless catches up to the extremes that SLRs are used to and factories are retooled for the new style of product. Then there will be another 5 years or so where the top and bottom SLRs (e.g. 1DX and 2000D) remain relevant and supported. All-in-all, it's going to be roughly 10 years (8 at least, 12 at most) before SLR is "dead".
This is, if anything, simply a sign that Canon knows the 7DmkII is outdated and no longer selling enough to justify making more units. Whether that means the end of the 7D line (extremely unlikely), a merger with the xxD line (quite possible), or gearing up for a direct replacement (most likely), nobody can say; simply discontinuing one body doesn't tell us much.