The Python 3 Readiness Project now lists [341](http://py3readiness.org/) of the 360 most common packages as Python 3 compatible.
Even that's underselling it really. For example it lists BeautifulSoup as not converted, but the link goes to BeautifulSoup 3.2.1. However, BeautifulSoup4 works great on Python 3. And for MySQL there's mysqlclient and several others, and since database packages usually follow PEP 249 pretty closely its very easy to switch. So in reality, rather than 341/360, its more like "everything worth converting has been converted." Or just "everything" for short.
this shows a superficial, almost entertainment-industry sort of view of a software development lifecycle..
in the latest Ubuntu Bionic with apps, building right now on a local machine, I see 143 python-xx packages installed and 43 python3-xxx ..
saavy package authors use import future and six to side-step the whole issue, while core maintainers struggle, and outsiders invoke a mob voice
Python 2.7 for LTS
It's not. Python 3 has overtaken 2 and there is no stopping migration to it now. Python 3.7 is a lot better than 2.7. Just on memory use alone, 3.7 is massively better. Sure, there will be some hold outs on 2.7 for a long time. That's fine.
Also, this is not the say that migration from 2 to 3 was handled well. It wasn't. Python 3.0 should have had backwards compatible features like allowing the 'u' string prefix. Indexing byte strings should have returned length one byte strings. Byte strings should have supported at least a minimal amount of %-style formats. Etc.
That has all been mostly resolved and is in the past. Mistakes were made because, shock, the Python core developers are not perfect and didn't foresee all the migration issues. However, there is no way that we are going back and reviving the Python 2.x branch.