Even without large increases in density, battery technology is "good enough" now to support touring ranges comparable to or superior to most gas bikes, and high charging power with relatively low cell charge rates .. but only in an expensive, heavy bike.
Large increases in density and reductions in cost ARE required for large batteries in a relatively inexpensive small bike. Keep in mind that "small" in a gas bike is still pretty large for Zero: a CBR250R weighs ~360 pounds with a full tank, a CBR500R weighs ~430 pounds with a full tank.
Zero uses pretty dense batteries now, ~170 Wh/kg. However, a 15 kWh Tesla-style battery using denser cylindrical cells would
likely weigh around 200 pounds, about the same as Zero's 10 kWh ZF11.4 battery. Tesla bulk charges their batteries at approximately 2C, so this battery could accept a 30 kW bulk charge rate from DC QC. It's possible that this charge rate would require additional cooling, which would increase weight.
So this gives us a 400 pound 15 kWh bike with existing technology, 100 miles of highway range or 200 miles of city range, and it could accept an 80% charge (80 miles) in 30 minutes. Tesla's cost for assembled packs are rumored to be in the $250-300/kWh range, so our pack would cost around $4500.
Faster and lighter than a CBR500R, decent highway range, and relatively quick charge times ... with existing technology. A 150 mile highway trip would take 2 hours to ride, 30 minutes to charge midway through .. that seems pretty reasonable to me.
None of those requires new technology, only the will and financial commitment to make it happen.