We have set up a new server with version 1.15.2 and by now updated to 1.16.1.
We aim to keep up with updates and update to new versions ASAP
The longterm plan is to keep the same map for 5 years (2025) and then re-evaluate (keep more 5 years if nothing has changed)
nether is reset since 1.16. (nether update) server is and will stay whitelisted
While Vanilla servers update, CraftBukkit servers will wait for an appropriate CraftBukkit version.
Until then don't update to 1.6 - use 1.5.2 until we say you can update.
1.6 requires a new launcher, You can still use that with 1.5.2.
Download the new launcher @ Mojang Help Website
When you have the new launcher, make a new profile or change the default one, select 1.5.2 as your version and you're set.