Earlier quoted context omitted.
No. If you take MongoDB and offer it as SaaS, the additional software that's part of your offering, such as monitoring, backup solutions, etc, have to be open-sourced, or you have to make their code available (since the chair of OSI defines what's open source).
I just had a call with MongoDB sales yesterday, and specifically asked if the licence changes impacts us, where we use Mongo as a datastore for our application, but we're not offering Mongo itself as a service. They were very quick and clear to say that the change is about those providers offering Mongo itself as a service. Using mongo in your stack to provide your service is not implicated at all. The only grey area…
Source: 1 data point; the company I work for's legal team just said "no".