Masker explained that even after game compression and asset removal, the client size is expected to be close to 100GB and that game patches can be several gigabytes each, or even up to 20GB if they decide to do a file type re-factor:
"The game compression and asset removal is unlikely to yield such high gains that we will be able to reduce our client size to 30-40GB. The size and number of assets that are left to deliver means that our client size is much more likely to be 100GB."
"Also, yes we are optimizing game patching for speed and to only deliver diffs, but this is unlikely to reduce actual patch size," he continued. "Again, each patch has 100s of assets, each of these assets are at times 200mb, this leads to 2-6gb patches, and if we end up doing a file type re-factor and have to re-download 30-40% of the assets on the hard-drive, then the patch will be 14-20gb."
Source: PC Gamer