Hello, I'm new here. I can bring some explaination of the French situation (I'm French from Castres). Don't worry too much about Lyon or other clubs. Despite many top14 clubs go beyond the salary cap (Racing, Toulon and Montpellier are suspected), few teams will be able to hire Sarries players. Lyon is not as good as it seems. Their ranking this year is mostly due to the world cup. They had really bad games since 1 month.
Also, the French players quota is increasing (well kown as 'JIFF', for players coming from the French academies). So I think that sarries superstars will mostly stay in the UK.