It isn't a question of elasticity of the dash material it is a question of quality of the adhesive. Several people have talked about the black defroster vent coming detatched on the ends, this is a sure fire sign of impending failure and a $700 dash job.
Most modern dashes have few problems with cracking. Besides dashes usually crack in the winter when the material is subjected to drastic temperature cycles caused by daytime sun and freezing night temperatures where the material becomes inflexible and brittle.
