French and Belgian strains and cellaring...

Given that most of these French and Belgian strains have optimum fermentation temps usually 60-70, what is everyone's experiences with cellaring batches at lager temps, or even near freezing. For instance, WLP072 has optimum temps 63-73, but for a biere de garde you would want to condition at a much lower temperature for an extended period of time (months). Will the yeast still be performing at these lower temps, what effects will it have on the brew? Thanks for any advice or input.