Out of interest why do you say it will be better? I could be / probably am using the wrong stat tool but this is what i get using a triple attack hero (eg:athel) as a test
Bosses:
GS:
78.4% chance to proc 2% at least once per atk
35.2% chance to proc 2% more then once per atk
WM: 3x attacker = single attacker
60% chance to proc 4%
So unless the 2 masteries have a different damage cap on CB it is likely GS on triple/quad attacker will still be better. Anyone using double attackers with GS will probably want to look hard at WM though (64% vs 60%).
However, outside of CB things are completely shaken up with both masteries having different benefits. Suffice to say GS isn't necessarily the auto-pick choice after this change. Assuming numbers do'nt change before release ofc.
https://www.socscistatistics.com/tests/binomial/default2.aspx