From my point of view, i understand that focusing on V4 is the best way to publish it, but as seen with the v3 experience, i recommend you to avoid this way.
Before explaining my though, i feel the need to present a little bit of myseft.
First of all, sorry for my english, i'm not a native speaker (frenchie here

). I'm an informatic engeneer which is currently employed by a firm to develop software in java (programming language). So i understand that focusing on one task only is the best way to achieve it.
From what i felt from the v3 waiting, i'm scraed of two things:
1. the lack of communication. From times to times we got a sneek peak version. that's perfectly fine, but we (the users) got nothing to play with.
2. the very long way to go. As Xpadmin says, there is no planned date yet. I understand that point perfectly as roadmap in development are generally done using almost a random time to implement a task: estimates are not easy to do.
As user (and as developper too) i prefer the way microsoft, google or even some other gaming company (like the one behind ark - survival evolved) works.
You provide an empty shell for user at first. There will be nothing in it, but whatever, you need something to start.
Then when fisrt feature is ready, provide it as soon as possible to early-adopters. they will know that this is still alpha/beta code and might experience crash. If you use a redmine/jira solution to track your issue, let the early adopter creates tickets for you. You will probably found bugs at earlyer stage than when it will be fully publish.
Yes, you will probably have to get one or two people to checks for duplicated issue or just to check if this is not a keyboard/computer issue. but trust me, a bug found earlier is easier to fix.
As microsft did for Windows 8, and 10; as google/mozilla do it for their browser: feature came one by one when they are ready, not a full package without public alpha/beta test.
Using this way, you will proove that your are still doing something for impatient user.
So for me, both of your strategy can be accepted, but none of them will get my vote.
If i was the planning leader, i will ask you to provide the new girl mesh as soon as possible (v4.0), then the new environment (v4.1 for first history from 2.1 scene, then some patch to complete the story step-by-step), then the second story (v4.2)...
I don't want to blame anyone, that's just my two cents about your roadmap.
Sorry in advance if you feel offended by my though.