It might take a bit more refined development to do the 60mph, I doubt any company will do it. Most likely you would need a motorcycle helmet and a licence to take it on the road in Germany anyway.
I'd be happy to take that bet, and the first guy I'd be looking at to do it, would be David Twomey, the creative force behind Juicer bikes. ( Not Juiced bikes )
http://www.juicer.bike/David's machines are basically handmade, are gorgeous retro creations, and he's currently using 3KW motors in his highest performance models. I wouldn't doubt that he's already surpassed 60 mph, but since this isn't capability that can be legally claimed for a production E-bicycle, you can't blame him for not blowing that particular horn too loudly.
Here's more info on the development of Juicer bikes. I personally think that they are the best looking, best engineered "custom styled" , recreational street machines around.
https://www.electricbike.com/juicer-e-bikes-king-of-the-boardtrackers/But E-bikes aren't about going fast, they are about low cost, low impact, local urban transport.
Consider my situation. My car can go at least 90 mph, but when I drive my car to commute to work in Chicago, an urban environment, it takes me 30 minutes to cover the 5.6 miles. That's 11.2 mph, average, but when I'm rolling, I'm traveling about 30 mph average. The majority of my commute time is spent stationary at traffic lights, behind a string of other lemmings, in their 90 to 120 mph capable cars. When I ride my old 3 speed bicycle instead of driving, (human powered, not electric), I can cover the same 5.6 miles in 35 minutes. I'm only traveling at about 12 mph, and with a little good luck and timing, I will only need to stop for one or two traffic lights. More than half of the world's population now lives in urban environments, like me. This is what E-bikes are designed for.
My speed is externally constrained, by external factors, like traffic. Having the ability to go 90, or 60, or even 35 mph adds nothing of value. Low operating cost is good for me, and low emissions is good for everyone. Being able to park anywhere, or push my machine inside the building for security, is a big plus too.
Ebikes are legally constrained to 15 mph in most European countries, according to what I've read, and to 20, (or 28 mph, depending on class) in the USA. Most of those being sold in the USA today can be easily modified, by a software update, to go faster, but this isn't really the point. Going outside those limits is forbidden for manufacturers. It's commonly done by individuals, and, so far, I haven't heard of anybody being prosecuted in the US for modifying their machine to go faster, but thanks to the exponential nature of aero drag, doing so heavily reduces cruising range. Personally, I'm quite content with a real 20 mph top speed on my bicycle, provided it comes with the right to coast through red lights, (here in Chicago, it "sorta" does), plus no required insurance, no required drivers license, no required registration, no required inspection, no required nothing and no paying for gasoline. I can legally ride on bike paths. I can even occasionally ride on the sidewalk, which I've been taking advantage of with the bicycle, since a major road on my commute has been shut down for the last two years for bridge work, but the pedestrian walkway has remained open.
Hub motors now generally include a 6 bolt standard mount pattern for disc brakes, and disc brakes front and rear are standard on the current crop of E-bikes, cable actuated for base models, and hydraulic actuated on high end machines. Drum hubs are also readily available.
Perhaps for reasons of price point, I haven't seen a lot of makers of E-bikes offering regenerative braking systems. Regen. isn't really efficient enough from what I've read, to make it worth implementing in these low speed, low mass vehicles. When I'm riding my human powered 3 speed bike, in the flat world that is Chicago, I can go all day without needing the brakes. The idea is conserve the energy in the first place, not to spend $1 to try to get 15 cents back in change.