ProtonMail already exists, has 2 million users, excellent security and architectural design, zero knowledge on the part of the provider, 2 factor authentication, optional two password setup (one for the account, another to decrypt the inbox), is located in Switzerland instead of the US, etc. It's also trivial to use, the importance of which can't be overstated.
In contrast, the new LavaBit is promising end-to-end encryption "later this year", as opposed to PM, which has always had it. It's concerning that a single SSL certificate was the only barrier between the users and total decryption. More competition is always good, but this looks like a significant step down from an existing service.