With Marie and Joachim now living in Copenhagen and some water under the bridge since this topic was last discussed I see some big changes.
Alexandra has lost some patronages and, I think, some of her public appeal of late.
Mary has continued focusing on her Mary Foundation and other royal responsibilities in her same old - same old way but spending noticeable time on overseas ventures.
Marie is poised and more confident and has steadily amassed patronages.
She has increased time and vitality for her work.
I see Marie growing increasingly popular. She'll be more popular than Alexandra for royal engagements in no time. Do others see the dynamics changing re: Marie's work vs Alexandra and Mary?
I'm not sure I understand why you feel a need to throw Alexandra into the equation

But yes, I think if Marie is allowed she could start stealing attention away from Mary. Keyword: allowed. IMO few (least of all Mary) is interested in having more focus on Marie and less on Mary. So I doubt she will be allowed to - even if it would be easier for her now that she'll be living in Copenhagen.