From my experience, most new bikes tend not to be as serviceable or durable, or as stout as 20+ year-old steel-framed bikes that have been given a full tune-up job and restoration of mechanicals. Plus old bikes in good shape can be found for CHEAP.
Anything with 7/8/9 speed parts, bar-end shifters(and less preferably, grip shifters) and either V-brakes or ISO-mount cable-pull disc brakes, will have near-ubiquitous parts availability, often even in bum-fuck nowhere, because they can be replaced with low-end parts found on crappy department store bikes. Get this with a steel frame and double-walled rims, with puncture-resistant touring tires(I recommend Schwalbe Marathon Plus Tour), and you can have a touring rig that can match the quality, durability, and reliability of various renown marques such as Surly, Marin, and Trek, without spending more than $500 or so, freeing up money for racks, panniers, tools, gear, ect. It will also have the advantage of not looking as shiny or new or expensive, reducing risk of theft.
That said, if the bike you already have is really the bike you want, even if it isn't precisely what you need, keep it. If you enjoy riding it, that matters as much as whether it will get you where you need to go. You're going to spend thousands of hours on it over its service life after all. If it was a compromise solution, IMO, you paid way too much and I'd look for something cheaper and used that can do the same thing, and learn to fix it up to your liking.
I built my own dream bike and don't regret it. Nothing on the market offered what I was seeking. You may find that to be your case as well. Mine is every bit as much a "car" as it is a "bicycle" though, having 3 wheels, an electric drive system, and an aerodynamic body, and while I haven't done a big tour with it yet, it has proven rock-solid reliable and I have over 80,000 miles on the frame using it to commute, visit job sites, and run errands. If I have to take a 150 mile "drive" with it, I think nothing of it. It has never left me stranded because I learned how to work on it by building it myself, always carried all of the tools I needed to rebuild it if need be, and chose mechanical components that are inexpensive, durable, and easy to find at almost any bike shop or big box store. The things most likely to leave me stranded are proprietary/unique parts like the steering spindles(one did fail at 40 mph once but I was able to drag it to a place where I could fix it with a welder), hydraulic front brakes(use a mix of motorcycle/ATV parts, and DOT3/4 brake fluid can be more easily found than brake cables), or air suspension.