I think that's a fair assessment of Kane actually Knarf. I'm sure the commentary I was listening to yesterday said something like it was his 50th consecutive league start, which, if you factor in the number of cup games he's covered this season as well, is almost unheard of in the modern game so it's no surprise he looks tired (which he did).
If we don't sign anyone in this window, even on loan, to cover for him, i certainly fear for his long term future in the terms of effectiveness as well as susceptibility to injury.
As I've said, if he plays the rest of the season as the sole striker, as well as the euros, he's going to end up needed an extended break to fully recuperate and recharge his batteries.