What steps can I take to determine feasibility of replacing a fairway wood with a "driving hybrid"?
I would ask three questions:
What is your skill level?
Generally, the lower your skill level, the higher the need to replace your long iron with a hybrid is. This is typical for beginners because they usually struggle with long irons. If you fall into this category, use the hybrid to replace the long iron, not the fairway wood. For more information on the construction of hybrids vs. irons, refer to this guide.
For those who have an adequate skill level to make further adjustments, continue reading.
What's in your bag?
Note: At a pro level, bag setup is very important. There is a crude correlation between bag setup and success(1).
My old bag setup was: Driver, 3- & 5-wood, 3-hybrid, 4-9 iron, pitching wedge, and two wedges (56° and 60°). Replacing a fairway wood with a hybrid would have been redundant.
My new bag setup (before adding my hybrid) was: Driver, 3-9 iron, pitching wedge, and three wedges (50°, 54°, and 58°).
There are many paths to go from here. Do you add a 3- or 5-wood? Do you add another wedge? Do you replace your long iron with a hybrid? Or...to my initial question, do you replace a fairway wood with a hybrid?
These questions can be answered in the next section.
What are your preferences?
A lot of golf is preferences and specific to an individual golfer. With the questions presented in the last section, preferences will help you answer those questions.
If I were a short game enthusiast, then I can add another tool of the trade with another wedge. For me, my choice would be a 62°.
If I were a beginner, or otherwise have a low skill level, then I would replace a long iron with a hybrid (see the first section for more info) before I replace a fairway wood with a hybrid.
For me, I'm not keen on using a fairway wood. I don't really have a good reason...just a club I prefer not to use often. This was the motivation for the initial question: Would a "driving hybrid" be an adequate replacement to a fairway wood?
If you are serious about replacing a fairway wood with a hybrid, look at this Golfsmith article. According to Golfsmith, my 19° hybrid is equivalent to a 5-wood. As originally stated, I thought about delofting my hybrid. According to Golfsmith, a loft of 14-16° would be equivalent to a 3-wood. If I do deloft, it would be to 17°.
Also, I was surprised to see my 19° hybrid be as long in height as my previous two 5-woods. My previous 3-hybrid was not as long in height as my previous two 5-woods. This was a promising start to my question.
Another consideration is how you address the ball and swing the club:
For a fairway wood, you set up in which the ball is forward in your stance, and sweep the ball off the ground.
For a hybrid, you set up in which the ball is in the middle of your stance and hit down on the ball (like an iron).
Furthermore, the hybrid is colloquially called a "rescue club." In the event you find trouble off the tee, the hybrid is more able to cut through grass and get the ball up in the air quickly. There is a place for a fairway wood; in light rough in which the ball is sitting up, a fairway wood is better suited due to its ability to sweep the ball.
I have a steeper swing, so a hybrid would complement my swing. Again, this is preference. A fairway wood has a place in many golfers' bags.
Note: These points are just a starting point for your consideration. More specific questions can be directed to and answered by someone who is experienced in this subject matter, like a fellow golfer or someone who can fit you to your golf clubs, for example.