Directly addressing the subject question - at what point do we declare EVs are popular in the US? Is it #s of BEVs sold in a year? A % of BEVs on the road? Multiple Super Bowl ads?
If we haven't hit "popular" yet, it seems we are getting awfully close....
Really interesting question! Here's a draft scale.
"Buyers" here means "new car buyers". I put "popular" at step 6 in a proposed 10 stages of a transition from all ICE to nearly all EV/PHEV.
10) Predominant - 97% or more vehicle miles traveled are traveled under electric power not ICE, over 90% of licensed vehicles are EVs or PHEVs, gasoline is rare enough that some areas can't easily be traveled to by ICE vehicles.
9) Dominant - 90% VMTs electric, 80%+ licensed vehicles EV/PHEV, charging is far easier to find than gasoline
8) Ascendant - 50% VMTs electric, 75%+ vehicles sold are EV/PHEV with no subsidies needed, charging is findable for almost any journey in US (range anxiety dead, excepting old farts). ICE owners probably complaining about fewer gas stations available.
7) Leading - 50%+ vehicles sold EV/PHEV, 90% of on-road locations in US accessible by 90%+ of EVs/PHEVs using ranges discounted for used batteries. Probably some gas stations under economic pressure unless they shift to charging, but still the majority of VMTs likely ICE.
6) Popular - 2/3 or more of buyers state they prefer EVs/PHEVs to ICE, majority of buyers who prefer EV/PHEV buy EV/PHEV, 75%+ of on-road locations accessible by 2/3 of licenced EVs/PHEVs per manufacturer stated ranges. Likely most vehicles on road still gasoline at this point though. Due to thin margins, convenience store industry websites probably discussing changes needed to survive electric transition if they haven't already done so, but fuel volumes sold still likely over 80% of peak. Subsidies might still be critical at this point for median buyers.
5) Desirable - Majority of buyers state they want EV/PHEV, but also say if conditions prevent them, they'll buy ICE instead.
4) Aspirational - EVs sell for more $ than ICE, but over 50% buyers say they can't afford one, or hesitate due to charging issues/ range anxiety. (now?)
3) Respect growing - EVs/PHEVs seen as specialty products and some non-techie, non-green consumers want them, but majority of buyers state they prefer ICE. (2018-202x?)
2) Niche only - Less than half of techies and environmentalists choose EVs/PHEVs, most people view them as weird and don't want them, but they're known to exist and enthusiasm is growing in viable consumer niches (2013-2017?)
1) Bleeding edge - few vechicles available, many barriers; buyers rare, most people have never seen an EV; DIY is a thing. (1990s-2012?)
Maybe we're in 3 and 4 at once for now?