I have experience of a similar service a the W London where the concierge was contactable via Whatsapp. It worked relatively well as I received replies to my queries and actually the opposite was true of the same concierge team when I went to speak to them directly in the lobby - it took ages to get the information I needed and the one request I asked in person (to put some champagne on ice in my room for mine and my wife's anniversary - asked as we left for a meal and a West End show) was forgotten about/ignored.

Let's hope the Accor properties get the balance right between personal touch and modern technical innovations. At least Whatsapp isn't produced by the Accor IT department so might actually work!