My 7yo is pretty big into minecraft and lego both. We have close to 30k bricks in our inventory, and he did get a minecraft specific lego set for christmas. We have a LOT of fun building things from minecraft into lego sets and vice-versa. I thought that he would prefer to build things in the virtual world (prototyping etc) before building in lego, but he really enjoys the physical process in lego and then trying to make the virtual (and at times more restrictive) blocks in minecraft.