How Can Brand Marketers be better prepared for the constant changing mobile advertisement environment in terms of mobile device design, OS ....etc?

I did not understand your question exactly because it is comprehensive and prefers to be more specific, but in any case, marketers should always follow the changes and the design and advertisements are modified and updated quickly in line with the brand and its message.

Keep doing market research

keep learning new technologies and upgrades so that u can reach out to customer first

 In case Using of  modern technology and social media will improve deployment and generate faster profits

In mobile advertising keep your message short and simple. 

May I ask how did you come to such conclusive question about changing mobile platform/OS?

:)

1) If you are a marketing expert cum techie, you wouldn't be asking this. Because between Android and iOS updates till now, the only thing that has changed from marketing perspective,.......is....nothing!

2) Terms of service and wholesale advertising rates on different APPs in both stores are almost similar.. So.. No change there too..

3) Most web stores/commerce sites are either fully mobile enhanced, or on their dedicated apps..so.. No change there too..

4) In browser experience on chrome/safari/firefox .. No change :)

you should consider revisiting the mobile marketing arena and research on the trending strategies instead. That would be very helpful for any marketing plan that you might be working on.

thanks

as far as i am concern, OS wise most of development focusing on mobile friendly design which is a responsive mobile friendly design / web