For our cloud 1 customers, they'll be able to upgrade to our cloud 2 offering, but in the meantime, their existing installations get the same 24x7 coverage and service we've been providing for years.
As for how this will be deployed, it will be a seamless transition for our cloud customers when we do so. Data, monitoring and analytics companies replace their backend data planes multiple times over the course of their lifetime.
For our Enterprise customers, we'll provide an upgrade path, but not until this product is mature enough to ship an on-premise binary that won't get a chance to get upgraded but for a few times a year.
The only difference here is that we're doing it as open source. They always do theirs behind closed doors. I'm sure most of our users and many of our customers prefer our open source approach.
Your time series data doesn't even need to be touched, it'll "just work" after the upgrade.
But by the 2.0 Release Candidate that was reverted so that it will use the same file format as 1.x, and the 2.0 functionality was backported onto that, so the upgrade path for 1.x to 2.0 is much simpler now than it was going to be.