People are making this much more straightforward than it would be, assuming that decent tactics are employed. Yes, if the zerg were allowed to take over the galaxy (assuming they are intelligent enough to save some species for food) then they would vastly outnumber any Geth and win via weight of numbers.
However, you're assuming that the Geth would let the flood get that far. In reality (ha!) they would probably also attempt to wipe out sentient (organic) life in order to contain the flood numbers. Either way, sentient life is screwed.
As presented, though, the Geth can barely fight humans without Soverign's help, so they wouldn't be able to restrict the supply of hosts to the Flood. Flood still win.
The real question to ask here, of course, is who would win out of Flood and Zerg..
However, you're assuming that the Geth would let the flood get that far. In reality (ha!) they would probably also attempt to wipe out sentient (organic) life in order to contain the flood numbers. Either way, sentient life is screwed.
As presented, though, the Geth can barely fight humans without Soverign's help, so they wouldn't be able to restrict the supply of hosts to the Flood. Flood still win.
The real question to ask here, of course, is who would win out of Flood and Zerg..