I think it would be impossible to guess at this point, but as a Model Y fence-sitter, a new Roadster doesn't worry me. Design work on M3 has already ended, and are those people are likely already working on Model Y, the pickup, the urban transport, the semi, and the Roadster to varying degrees. In fact, final Model Y designs are probably waiting until Tesla sees how Model 3 production line works out, and whether tweaks need to be made. No point in replicating any sticky parts of the production process with the Model Y when they can learn from their mistakes.
Production is the bottleneck, and with the Roadster likely to be such a low volume car relatively speaking, I don't think it would have a meaningful impact on the full Fremont 1 million cars per year capacity. The M3 and the MY are the ones that will be fighting over capacity until addition production can come online.
I think this week has been a healthy reality check for a lot of Tesla fans. I think everything they're doing is going to help them meet the optimistic side of their production targets. Sadly that just means that not everyone can get the car they want as soon as they wanted it.
If "a few years" indeed means production starting sometime in 2019, then that's what I'd been bracing for. And if that means we don't see it until 2018 then that's fine too. But how Tesla will stagger their announcements and rollouts the farther they get from a 2-3 vehicle fleet, I think we can only guess.
