This definitely doesn’t have anything to do with a certain announcement of an electric scooter made by a certain large scooter/motorcycle manufacturing conglomerate.
So, a Genuine Stella has 2.1 gallons of fuel capacity, per Motor Scooter Guide. That’s just shy of 8 liters. The fuel tank on a classic Vespa or a clone thereof such as the Stella (except for the automatic Stella, actually) is mounted directly below the seat, very easily accessible.
Decently high power hub motors in the correct size for a later classic Vespa or a clone, 10", are available - this one claims to be 6 kW rated power (they have test results showing it going as high as 8 kW output power), which is just about the right amount of power, too. I’m sure a major manufacturer would have the resources to find something higher quality than that, too, maybe even with the right bolt pattern so you could maintain the spare tire’s usefulness. Or, don’t, and put a saddlebag where the spare tire was (you could put the 12 volt battery, which normally resides inside the spare tire well, where the oil tank used to be, or don’t even bother with a 12 volt battery).
Panasonic claims 676 Wh per liter for the NCR18650B, which is actually one of their older cells. Even if your cell packing assumes square instead of round cells, you’re looking at 532 Wh per liter. So, by my calculations (looks like Panasonic’s volumetric density calculations were based on 3.3 Ah/cell), that’s 4.2 kWh that would fit into a 2.1 gallon hole. Even if you adjust to aim for 72 V pack nominal voltage (meaning a 20S layout), you’re looking at 340 cells fitting there, which means 4.0 kWh. And, you wouldn’t really need that much battery, so you could just make the pack lighter (I mean, 340 cells is basically 16.5 kg, not counting the pack’s own weight, so that is too heavy for regular swapping IMO, you want to stay below 15 kg for the whole pack). If you did put 4 kWh in there, though, I’m sure you’d have well over 100 km range.
Oh, and that pack would be mounted directly below the seat, very easily accessible, meaning battery swap becomes trivial.
Oh, and you even get to put a saddlebag where the engine used to be, increasing storage space over the ICE model.
Again, this thought definitely has nothing to do with the Vespa Elettrica and its lame specs and lack of battery swapping. No sir, nothing at all.