If it's true, i don't think it's pressure from Tamron since the Tammy IQ isn't as good as the 24-70LII
I would bet that if Canon does release this the IQ will not be as good as the mkII but will rival the Tammy at a similar price to the mk1.
Why? Because if the IQ is on par with the mk2 and with IS included, then those who bought the mk2 would be kinda disappointed and this will be prices too ridiculously high.
If they released it with the mk1 IQ but with IS, then at least for people who have IQ in mind, they buy the mk2, for those who want to do video and need IS, they buy this…