My understanding of the email is that if you credit your Fairmont stay to the Fairmont President Club, the stay will be added to your Accorhotel year when they merge in July.
Here's the text of the email:
Dear Defurax,
As you may be aware, in July 2016, AccorHotels welcomed Raffles, Fairmont and Swissôtel Hotels & Resorts to our collection of luxury properties.
The addition of these renowned brands offer our guests even more choice with iconic and celebrated hotels such as: The Savoy in London, Raffles Singapore, The Plaza in New York and Le Royal Monceau - Raffles in Paris.
And now there is even more to get excited about because, as of 2 July 2018, Raffles, Fairmont and Swissôtel Hotels & Resorts will welcome Le Club AccorHotels members globally! From this date, members will receive all the benefits of their Le Club AccorHotels membership including Status and Rewards points for every eligible stay.
To reward members during this interim period, if you join the Fairmont President Club and/or Swissôtel Circle* loyalty programmes now, and stay at these brands from 1 January 2018, we will add these room nights to the total of your membership activity in contribution to your overall Le Club AccorHotels status as of 2 July 2018.
We remain at your disposal if you have any questions about the upcoming change.
We thank you for your continued loyalty.
Regards,
Isabelle Birem
Senior Vice President, Le Club AccorHotels