Please, AMD, I'm begging you, match up the APU numbering scheme with the generation of CPU they go with.
While its not exactly entirely straightforward, the fact is, the vast majority those buying these processors probably won't care, as they are not really targeted at the "performance" market. These are lower-end processors for more budget-oriented systems. If someone is after optimum gaming performance, they should probably be looking at something else. The vast majority also won't even have any clue about AMD's Zen 2 architecture offering IPC improvements, or Navi for that matter. The only ones who might care are those following tech hardware releases, and they will know for that reason, so it's a bit questionable how much it actually matters.
Adding HBM would increase the price considerably. However, if the performance justifies it I'd pay. I'm saving money and waiting for a good all-around APU from AMD. Four ZEN2 cores with SMT is enough. It's the iGPU part that's unsatisfactory. AMD should make something like Kaby Lake-G processors, but not in BGA package.
Even with HBM, these APUs would have limited graphics performance, since they just don't have enough graphics cores to compete even with lower mid-range parts. Maybe this rumored Vega 15 APU could get up around RX 560 / GTX 1050 level performance with HBM memory, but those were fairly low-end graphics cards even when they launched a few years ago, and you can get nearly double the graphics performance out a dedicated Radeon RX 570 for as little as $130 now, and there may be even more performance available in the budget range once AMD fills out their RX 5000-series lineup.
On that note, you probably wouldn't be saving much going with an APU with onboard HBM2 memory. I don't know about current pricing, but a couple years back when Vega launched it was around $150 for 8GB of HBM2. It's probably less now, but still might raise the price of a $150 APU to something closer to $250. And you would still likely be getting far less performance than one of those $130 RX 570s combined with a $120 Ryzen 2600. With graphics hardware in this performance range, Zen 2 isn't going to matter as much, since any recent games are far more likely to be graphics limited than CPU limited, even with the previous-gen Ryzen parts. Having those additional cores and threads will likely be beneficial down the line as well, since games are becoming more heavily multithreaded, and next-year's consoles will apparently be utilizing 8-core, 16-thread processors.