Everything is possible. It depends on what members decide on and different possibilities. It really does depend on the House.
When we talk about presence in the House, a lot of the time when debate is happening, the House is not full; it's mainly during question period or when votes take place. One of the things that concerns me about saying “okay, you're only allowed 40” is parliamentary privilege, which you brought up earlier. Who determines who that 40 is?
When I send out an invitation or a recall of the House, it is to everyone. It's not up to the Speaker or any rules to determine who doesn't show up or who can or can't show up. That would be one of my main concerns.