If anything serious starts to go down at least half of the Army will defect to Guaido. But that opinion is predicated on the belief that the PRC, Russia, Cuba, and Iran--Maduro's string-pullers--will decide not to engage in a proxy war with the United States in our own hemisphere.
Both China and Russia are going to take a huge economic hit if Maduro goes down. I think VEN owes the PRC some $68-billion in loans. In order for them to back him militarily, they have to gamble that the incredible cost of war, far from their homelands, will reap dividends and help them recoup everything they've invested.
Is it worth it to them? Is Putin or Xi willing to get his country embroiled in a Western Hemisphere Vietnam to prop up an extremely unpopular regime? Even if it's only to divert attention from their actions respectively in Ukraine and the East China Sea? I think it's a real longshot.