I know there are a multitude of inputs into the decision making process for these things - including, of course, ratings - but it's hard to imagine a world in which there were so many "serious" Democratic candidates that any news network planning to broadcast a debate would just shrug its shoulders and say, "oh well, I guess we gotta have two." They'd choose the "top" 5 (however they would decide to choose them) and tell the rest to piss off. Related, most of the candidates would be completed ignored by the Sunday shows instead of each one getting multiple turns.
The Republicans must be heard. All of them. Again and again and again and again.