[jtrtoo]

Everyone is going to have a different answer to this (and that answer may evolve as the business does).

All business decisions like this are about what level of abstraction is appropriate for us (today) and what level of specialization is conducive to our strategy[1] (today).

In some cases the infrastructure outsourcing question won't even be particularly important - a wash essentially regardless of the path taken (in the bigger picture of the enterprise's mission anyway). Other times, it'll be - effectively - paramount.

[1] Or current priorities, concerns, strengths, weaknesses, biases, pressures, risks, opportunities, competitors, etc.