Well, yeah, there's an endpoint to development, right? The oldest implementations of Epic - UW, Allina, UMN, and somewhere else went through that cycle. Even when UMN got smart about it and started dragging it's feet, it'll happen. The way it works is that when the development of order sets and protocols more or less ends, they will keep the one, but every other task pretty much is handled by HIMS or alternate work nursing staff (cheaper by far). Some get positions with Verona in the end or with the contractors, there's a group in Minnesota, Allina, that basically outsourced all that maintenance to a consultant company. I'm sure it'll come around once your implentation is mature. Hell, you might start that consulting company yourself!
But yes, don't take my word for it. Ask the long term Epic pharmacists what happens to them. There's 5 and 10 year benchmarks for staffing. This is usually achieved through natural attrition, but if not, what happens depends on how the DoP deals with vestigial personnel (those pharmacokineticists had to go somewhere, right?).
If you are going to make a life in this industry between pharmacy and IT, I would do what the IT old timers do. Work, but use the opportunity to play around and learn the systems such that you have a command over them and not them over you. Leave knowing that part of your compensation is the ability to use the hospital as a test learning lab for technology. If you talk with IT consultants, they will take time to learn on company time. That way, when the inevitable happens, either they are in a position where they have to be suicidal to lay you off or you're comfortable going it alone. That's really true of all pharmacy, but technical pharmacy is one where if you know something, that's what makes you hireable more than a warm body. It's not rent-a-clinical-pharmacist by any stretch.