UPDATE 11th June 2020: The Call of Duty: Modern Warfare Season 4 download has gone live - and it's huge.
The download weighs in at 45GB on PC, 32.375GB on PS4, and 44GB on Xbox One. However, some Xbox One users are reporting having to download over 84GB with this morning's update. Activision has said it's investigating the issue.
Activision has said that once installed, the Series 4 update will only take up an additional 4GB on consoles.
ORIGINAL STORY 10th June 2020: Infinity Ward has warned tomorrow morning's Call of Duty: Modern Warfare Season 4 update download "is going to be large".
In a series of tweets, Infinity Ward community manager Ashton Williams said the developer was reducing the overall disc space that Modern Warfare and Warzone take up, which is pushing 200GB at this point, by compressing assets.
This means that once installed, the Series 4 update will only take up an additional 4GB on consoles. However, players are still faced with a hefty download when the update goes live at 7am tomorrow morning, UK time.
Williams pointed to the option for console players to uninstall content packs for modes they're not playing in order to free up space (Spec Ops, I'm looking at you). However, this option is not available to PC players.
Williams said Infinity Ward is "continuing to sweep all assets to make size reductions where we can, and also further optimise future patches for size", which hopefully means future Call of Duty: Modern Warfare downloads won't be quite as big.
Infinity Ward has come under increasing pressure over the enormous install footprint of Call of Duty: Modern Warfare and Warzone, as well as the enormous downloads required to update the game.
If you have the complete Call of Duty: Modern Warfare experience on your PlayStation 4 (pre-Season 4 update), it takes up 190.1GB on your hard-drive.
This means that after you've downloaded the Season 4 update, the full-fat Modern Warfare will take up just over 194GB. This install footprint dwarfs that of most other games - and the enormous size of Call of Duty updates is an issue for many who have restricted bandwidth.