Below is a quick overview of the 2021 K2 snowboards lineup.
First I will take a look at any new boards for the 2020-21 season, and any old 2019-20 boards that are exiting.
Then I'll look at each board and put them into the categories where I see them best fitting.

New 2021 K2 Snowboards
The new boards for 2020-21 are:
Exiting 2020 K2 Snowboards
The 2020 boards that aren't returning with a 2021 model:
All 2021 K2 Snowboards by Category
I have categorized K2's 2020-21 collection below. This is according to the categories here at SnowboardingProfiles.com and not necessarily the same as how K2 labels them.
Of course these are only broad categories as every board is different, but this is a rough guide.
K2 BEGINNER SNOWBOARDS
Men's
Women's
K2 PARK/FREESTYLE SNOWBOARDS
Men's
Women's
K2 ALL-MOUNTAIN-FREESTYLE SNOWBOARDS
Men's
Women's
K2 AGGRESSIVE ALL-MTN-FREESTYLE SNOWBOARDS
There isn't a K2 board that strictly fits this category, IMO, though the Medium and Afterblack could both be used for this style of riding.
K2 ALL-MOUNTAIN SNOWBOARDS
Men's
Women's
K2 AGGRESSIVE ALL-MOUNTAIN SNOWBOARDS
Men's
K2 FREERIDE SNOWBOARDS
Men's
Women's
K2 POWDER & SHORT/WIDE SNOWBOARDS
Men's
K2 SPLIT BOARDS
Men's
Women's
K2 YOUTH SNOWBOARDS
Summary
So there you have the 2021 K2 snowboards.
With 6 new boards in and 3 out, there's a net increase of 3 boards. The Dreamsicle pretty much looks like a name change for the exiting Bright Lite and the Manifest Team is very similar to the Team but a little souped up.
But the other 4 new boards all look like genuinely new boards. The Alchemist slots into the space that the Joy Driver leaves, but it's a different enough board not to be just a name change. And the Niseko Pleasues fills the gap where the Eighty-Seven leaves, but again, different enough that it's not just a like for like swap.
For all of Snowboarding Profiles' K2 reviews, check out the link at the button below.