Rename fiu-vro to vro is still needed and there is consensus that it should be done.

I wonder what's up with these rename requests that takes years to complete. What's hindering it?

Not much any more.

I started a thread about it a couple of weeks ago - https://lists.wikimedia.org/pipermail/wikitech-l/2015-August/082914.html

And there was an agreement, more or less, that it used to be very scary, but it shouldn't be very scary in 2015. be-x-old was moved to be-tarask a few days ago, and except for a few non-disastrous fixable glitches, it worked - see T11823. There are probably a few more coming.

In T31186#1624273, @Malafaya wrote:

I wonder what's up with these rename requests that takes years to complete. What's hindering it?

For years people were waiting on a solution to rename the database itself (this is quite hard due to issues involving external storage databases). What we are instead trying to do now is detach the database name from the domain name and just change that instead. It's been tried on a private special wiki (chapcom -> affcom) and I've seen no complaints, and we also recently tried it on be-x-old -> be-tarask wikipedia. Most things there are fine, but there's still a few issues involving interwikis (I looked through this nightmare yesterday and will be posting on T111853 later), wikidata integration (site table - see T111853), some external services (including T111818 and T111850 for CX, mostly cleared up now and will hopefully be fixed by the end of today) and the SiteMatrix extension (T111876).
I would like to get the remaining issues from be-tarask sorted out and a full list of things needing to be done completed (it's mostly written and up on wikitech, but waiting on some remaining details from the issues we found after the be-tarask move) before renaming another on a project-language wiki (i.e. I think a special wiki like T31919: Move the wiki of WMEE should be fine).

In T31186#1625347, @Krenair wrote:

In T31186#1624273, @Malafaya wrote:

I wonder what's up with these rename requests that takes years to complete. What's hindering it?

For years people were waiting on a solution to rename the database itself (this is quite hard due to issues involving external storage databases). What we are instead trying to do now is detach the database name from the domain name and just change that instead. It's been tried on a private special wiki (chapcom -> affcom) and I've seen no complaints, and we also recently tried it on be-x-old -> be-tarask wikipedia. Most things there are fine, but there's still a few issues involving interwikis (I looked through this nightmare yesterday and will be posting on T111853 later), wikidata integration (site table - see T111853), some external services (including T111818 and T111850 for CX, mostly cleared up now and will hopefully be fixed by the end of today) and the SiteMatrix extension (T111876).
I would like to get the remaining issues from be-tarask sorted out and a full list of things needing to be done completed (it's mostly written and up on wikitech, but waiting on some remaining details from the issues we found after the be-tarask move) before renaming another on a project-language wiki (i.e. I think a special wiki like T31919: Move the wiki of WMEE should be fine).

Just in case it weren't clear, thank you very much for this, @Krenair and everybody involved!

Thank you both for the explanations.

Just pinging.
be-tarask seems to be ok, but were there any significant problems? Would it be possible to have fiu-vro changed to vro now?

Yes, there were problems:
T111822: [Bug] Adding sitelinks at be-tarask Wikipedia doesn't work
T111853: The href of be-tarask: interlanguage link points to the be-x-old domain
T111876: Figure out how renaming languages without database names is supposed to work with SiteMatrix, and implement for be-x-old -> be-tarask
T111895: MassMessage input lists need manual updates after a wiki's domain name changes
T112285: ContentTranslation link adaptation is mostly broken when translating to be-tarask

It's possible to leave fiu-vro/vro in the same position, but I want to avoid it.

Change 527914 had a related patch set uploaded (by Fomafix; owner: Fomafix):
[operations/dns@master] Add 'vro' as alias for 'fiu-vro'

https://gerrit.wikimedia.org/r/527914

Change 527915 had a related patch set uploaded (by Fomafix; owner: Fomafix):
[operations/puppet@production] Add 'vro' as alias for 'fiu-vro'

https://gerrit.wikimedia.org/r/527915

Change 527914 merged by Dzahn:

[operations/dns@master] Add 'vro' as alias for 'fiu-vro'

https://gerrit.wikimedia.org/r/527914

valid code per https://iso639-3.sil.org/code/vro

mapping also in https://meta.wikimedia.org/wiki/Template:List_of_language_names_ordered_by_code

vro.wikipedia.org has been added to DNS

vro.wikipedia.org is an alias for dyna.wikimedia.org.