Hi there,
I can't address the Puritan DMin specifically, but can speak to adjunct teaching. There are likely to be more adjunct roles (and less full time roles) teaching in Christian colleges and seminaries in the future, frankly because adjuncts are so much cheaper than residential faculty, and there is a massive oversupply of potential teachers. In particular, adjunct support for online programs will be a growing area of need. Unless your area is Pastoral Theology, a DMin is not the best preparation for these roles however. Most residential adjuncts will have PhD's from quality institutions; if not, they will generally at least have a ThM in the subject they are teaching. This provides a level of specialization in the field that a DMin won't give you. Most of our online adjuncts at WTS have (or are getting) PhD's; though some have ThM's and some who teach in more pastoral issues have DMin's. However, not all online programs require the level of excellence from their adjuncts that we do.
One area I wish more people would think about is the mission field. The need for theological education around the globe is enormous, and operates at a wide range of academic levels, from barely literate to PhD candidates. Someone who supports himself through pastoral ministry who has teaching gifts and a church that shares the vision could easily find a partner institution in a Majority World country, where he could teach regularly at his (or his church's) own expense (say 2-3 times a year). A ThM would often be a good further equipping for that task, but in some locations, anyone with a good MDiv will be a relative expert. Even better if you speak the language.
