I'll be needing a new phone in the next 6 months or so. Will be sad to leave the Apple ecosystem, but if they are still selling years old tech in the SE, I'll sadly be leaving.
The SE combines the guts of a 6s with the form factor and display of a 5s. So "years" depends on which part of the phone we're discussing. Yeah, it's older tech, because that's part of the deal - lower tech, lower price. If the tech is too low, yeah, you may as well walk. I don't think you'll have to, though.
The SE was introduced in March 2016, half-way between the introduction of the 6s and the 7. It was refreshed in March 2017, but the only change was the bump-up in storage capacity. I wouldn't expect another refresh until March 2018, at which time it would be logical to have the guts of a 7 and the display of a 5s.
Typically, the entry-level phone is the year-old model. The SE may turn out to be an exception to the tradition, rather than a continuing product. So if Apple holds true to old form, the 7 and maybe 7 Plus will be available in fall 2017 at a new, lower price, and the SE will disappear altogether from the shelves in Apple's more affluent markets (going from Special Edition for all markets to Special Edition for Emerging Markets).