In Vietnam, there were 58k US dead for the whole war. US military dead in WWII was 400k. 30K dead/month gets you to WWII losses in a little over a year. US dead in Afghanistan and Iraq was much less.

I'm wrong about a lot of things, but I don't think the US public would accept losses on the order of 30k/month: there would be massive demonstrations and congress would likely act to cause disengagement.