As these precons are themed after the two returning planes (and IIRC Maro said in his blog that the “vanilla matters” of Muraganda is quite difficult to design for nowadays), it probably will be dependant on the set in question. I can see 5 precons for the Tarkir set, for example.
But yeah, 2 per set is much more feasible and hopefully the main way forward. The only downside I see is that you can’t play a full precon pod with one set.
I did not expect Duskmourn to play a part in this story at all. The thought of Valgavoth as a team principal with his followers as drivers/members is rather funny.
There are quite a few plot threads and possible endings for this story. Maybe the Aetherspark really is unstable and whoever uses it ends up at the Edge of Eternities. Or Valgavoth gets it in his wings and begins to domesticate other planes to really become the current big bad. Or something completely unexpected happens.
Whatever it is, I’m now even more interested in the setting than before.