To be honest I was slightly concerned by how much KLM cut capacity over Christmas/New Year. Now I know demand falls off, even more so at the moment, and if the 4th daily was axed I wouldn't have been too worried. But some days there was only one flight. In previous years IIRC all that was cancelled was the Christmas Eve nightstopper, Christmas Day and 1st Boxing Day departure.
I would think the 4th daily needs to become 7 days a week, 50 weeks a year rather than the current one/off arrangement before any CDG service is looked at. Any CDG service would obviously lead to AMS capacity being cut, and frequency wise anything less than 3xDaily would seriously reduce the number of connecting opportunities.
I would love to see CDG but with the 4th AMS flight not operating all the time, and the current economic climate, I think its far better, short term at least, to focus on the AMS service and getting that 4th daily operating all year