I'm not clear on how any of this will lead to a recession. Why will high Debt-to-GDP or government spending send the economy into a recession? Q1 GDP numbers were clearly affected by dismal weather (although still bad), but labor markets are improving markedly, and there are reasons for optimism. I don't see this as a very convincing bear case. For the bull case, see this post, from a guy who's been right about every…
It happens when the assets can't pay their interest payments any more.
For now interest rates are low, so the government can pay it's billed. Unfortunately, we hold a lot of short denominated debt. We should lock in these rates while the going is good. If interest rates spike up, the government will have to cut programs, borrow a lot more money, or increase taxes. It's a very negative spiral.
The reality is that nobody has been in our exact situation, so there is more speculation. Are we becoming more like Japan? Or Europe? And how might aggressive immigration help us?