A public option likely won't be much cheaper, her plan takes 10 years to implement which means it'll be left to someone else to actually complete it and that doesn't make much sense. They need to make sure everyone is covered, a public option still requires people to buy a public plan.
Her problem is making so wishy washy on what she supports but the idea that Bernie's M4A is going to magically come into existence as soon as a Democrat takes office is silly. The nominee needs to be more pragmatic so something actually gets done and so they don't lose.
Healthcare won them 2018. They keep fooling around and its going to become a losing issue for them in 2020.