Projects 'of a given size', yes. But there are small projects, projects for Windows, projects where the fleet is managed and deploying full venvs isn't done... etc.
The niceities of greenfield work and what ought to be done start breaking down as you get into heterogeneous systems where total system stability (lack of change ) is a big deal, and these fleets have been running for a decade or so. Imagine having to figure out deployments to a Python 2.4 environment in 2012 (I had this problem).
To misquote a famous statement, you fight the battle with the troops you have, not the troops you want, against the enemy you have, not the enemy you want. The reality is that it's often (usually?) not worth it to ship full venvs with Py3. It's often much better to ship Py 2.7 code (just your own code) and install your own libraries in the system library location.
The niceities of greenfield work and what ought to be done start breaking down as you get into heterogeneous systems where total system stability (lack of change ) is a big deal, and these fleets have been running for a decade or so. Imagine having to figure out deployments to a Python 2.4 environment in 2012 (I had this problem).
To misquote a famous statement, you fight the battle with the troops you have, not the troops you want, against the enemy you have, not the enemy you want. The reality is that it's often (usually?) not worth it to ship full venvs with Py3. It's often much better to ship Py 2.7 code (just your own code) and install your own libraries in the system library location.