Are there any discussions or plans about dismantling the LSST on Cerro Páchon once all it’s surveys are completed in the mid 2030ies, move it to the northern hemisphere, and equally map the sky there to have a truely complete catalogue of the whole sky with the same instrument, albeit under varying atmospheric conditions?
I have not heard of any plans like this (@ivezic?), although I have heard of interesting ideas to continue using the telescope in the south. Surveying the sky with different, more frequent, cadences — perhaps to target particular kinds of transient or variable objects (maybe even new types of objects discovered during the main survey) — over more limited areas than the main survey footprint would be a simple option. Adding new filters to look for particular features in stars would be another possibility.
I suspect it’s more cost effective to simply build another copy of the telescope in the north, rather than move it.
I also have not heard any discussions about moving the LSST after its 10 year survey – perhaps you already saw these, but here are two white papers about options for additional science with LSST into the 2030s.
“Astro2020 APC White Paper: Next Generation LSST Science”
“Astro2020 Science White Paper: LSST Narrowband Filters”
I never heard anyone proposing to physically move the Simony Survey Telescope and LSSTCam north. At some point, there was a rumor of a Russian oligarch proposing to fund a copy in Russia, but I haven’t heard anything about that in almost a decade. Even if we could move the telescope and the camera north for free, it would still take $60M/yr to operate the survey so it would not be a very cheap project.