I know the answer may be variable depending on the bike and parts, but generally speaking, how long can you expect an e-bike to last? Assuming you get one with a Bosch, Brose or Yamaha motor (the kind available on Trek, Specialized, Electra and Giant bikes), how long can you reasonable expect to keep that bike, with whatever the general maintenance is, before needing to replace it? 5 years? I guess the battery might need replacement first. I don't know how much that costs, maybe $500? Just some questions I had before I refine how much I am willing to shell out for my first e-bike. Thanks.
You left out my personal favorite "mainstream" motor line, Shimano STePS. Their 504Wh batteries go for about $600, 416Wh for under $500. I expect they'll be supporting their "older" (still OEM on many new models) systems for years, if not decades.
STePS systems have only been around since 2016, I believe, but I've ridden THOUSANDS of
trail miles on Shimano, Yamaha, Bosch, and Brose powered pedelecs in the past 5 years, and I've
never had a failure. The one Bafang mid-drive ebike I had for about 6 months in 2016, a Biktirx Juggernaut, did have some motor issues, but I'd gotten it cheap from CL's and it sold for what I paid pretty easily on Craigslist. Last I heard the buyer basically "lives with" the motor's intermittent problems - he doesn't ride much...
Edit: I also have a 2015 TranzX motor equipped iZip Sumo fat ebike (still going like the Energizer bunny), which has pretty much exclusively been my snow-riding bike for the past dew years. In its first couple years, however, it was one of my main, year-round trail bikes, and its motor didn't "fail" but had a weird surging issue. iZip sent me a replacement motor, which I plug-n-played myself in like a half hour, and it's been great since. The only other issues I've had with that 5 year old bike have been tiddlywink bike hardware stuff like hubs etc. Some cheap choices were made there...
Regarding the comment about aluminum frames having a 5 year lifespan, my 2002 aluminum alloy Stumpjumper FSR lasted 10+ years with no issues - it's still in my garage but hasn't seen trails for several years. I'm didn't jump many stumps with it (casual/recreational riding only), but I'd be confident taking it out today - 18 years later!