Welcome to the forum, Eric!
I'm not a Yamaha expert and don't have any specific advice for models or where to shop, but I'll throw in some thoughts that are a bit geared towards "buy for the present" as opposed to trying to predict what you might need in a few years. The general idea is that you can get a lower priced model that suits all of your needs now and then upgrade in the future for possibly less total cost than going all in right now. Plus, few if any people know what features will be in receivers in five years (or even next year). I bought my Pioneer Elite five years ago in 2009, and I'd never even heard of 4k displays or HDMI 2.0. Plus, features that are "advanced" today and only in higher end models tend to trickle down into the mid and even lower priced models in a couple of years. One thing that has been getting harder to find in lower priced models, though - is pre-amp outputs. So, you've got to consider how probably it is that you'll be getting an amp before you get another receiver.
These days, getting pre-amp outputs tends to put you into the upper mid-level range of receivers and price points, so you pay a premium for those. How sure are you that you want to get an external amp? If you get a receiver that has enough power to drive your speakers to the levels that you listen, then an external amp isn't going to add anything (except cost and weight
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). I bought two external amps (from Emotiva), and I can't tell a difference between using them or not using them at my normal listening levels. With a good receiver, I can't tell a difference at very high (to me) sound levels, and my NHT speakers aren't that efficient. Regarding Emotiva, I'll never buy from them again and wish that I never had - just one alternate viewpoint to add to the positive remarks that you've read/heard, no more and no less.
However, I totally understand the need to find out for yourself.
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If you know for sure that you want to get an amp before you get another receiver, then it absolutely makes sense to have pre-amp outputs as a requirement. Do you want just front pre-outs, or the full set?