If it's not, you'll receive a supplementary note together with the same indicating revision of benefits etc.

those notes could be old batch and they still keep in circulation. 

the revision to 8% was effective in Nov 2016. announcement in Oct 2016 >> read here

latest PDS on 1 March 2017 also stated 8% cashback.

i still getting 40+ cashback on 1 March 2017.  :thumbsup:
unlikely maybank to u-turn their decision this soon considering they went to media to shout the benefits and collabroation with Petronas Dagangan 

Maybank Islamic Bhd eyes a 27% increase in its Maybank Islamic Petronas Ikhwan Visa Card-i membership to 73,000 in the next 12 months following the card’s newly-enhanced features. 

furthermore, maybank must announce the revision at least 21 days before effective date.

I think this is the best CB card out there at the moment if you only pump Petronas

If you are a Petronas user, yes it is a must card to have. I asked my sister to apply for this card since she uses exclusively Petronas and Caltex.

It's actually you take CL from your conventional to Islamic. In another word, they don't grant any CL for your Islamic cards.
For e.g., your conventional is RM 10k and you ask for RM 3k for Islamic, so your conventional is reduced to RM 7k and transfer the RM 3k to Islamic.