Switching to a single front sprocket is certainly doable, and would result in a simpler 5-speed bike. The chainline would be acceptable in all gears. You can even try this setup initially by just not using the front derailleur, leaving it on the middle chainring. Depending on what gears you use, your existing middle chainring may suffice, or you might want a replacement single chainring with a tooth count between your current middle and outer rings. Consider a 3 or 5-speed IGH as well.