Is there a way to get the current version of the kernel for the Raspbian distribution, without installing it?
I don't really want only the number, I really would like a procedure to get it next year.
Looking for a generic way to determine the kernel version with out installing / running the Raspbian image appears a bit of a challenge. (I'll gladly change this answer if someone comments with a better way.)
If you look at the Raspbian release notes, you will see an occasional entry regarding the kernel. Unfortunately seldom is the kernel version included.
If you look at the Raspbian wikipedia page, you will find a table of release dates, Debian versions names and kernel versions. This page spans years of Raspbian distributions and (currently) only lags the available download images by about 3 months.
And (as @Milliways points out) you can download the *.info file for the distribution you are interested in. Start in this directory:
...then drill down into the release of interest, download the file ending in .info and search for "Linux version". Here is the entry from the newest Raspbian distribution:
Uname string: Linux version 4.9.59-v7+ (dc4@dc4-XPS13-9333) (gcc version 4.9.3 (crosstool-NG crosstool-ng-1.22.0-88-g8460611) ) #1047 SMP Sun Oct 29 12:19:23 GMT 2017
https://downloads.raspberrypi.org/raspbian/images/raspbian-2017-12-01/2017-11-29-raspbian-stretch.info contains details of the "latest", including kernel version.
The parent directories have all versions, so you would have to select the latest.
Packages file for the raspbian distribution, for jessie:
raspberrypi-kernel package version :
cat Packages | grep raspberrypi-kernel_
The interesting part is
1.20170703-1, this number can be found on the Rasperry PI's kernel page on gitub and search for the this release number. This will show :
Merge remote-tracking branch 'stable/linux-4.9.y' into rpi-4.9.y
In this case the kernel is 4.9.