An out of warranty battery failure would be utterly uneconomical to replace, which is one of the reason EVs in general take a massive depreciation hit. For example, it appears that the battery is more than half the NEW bike cost, not including labour. To use the Model 3, a $36k new car will need a $13k battery. Due to most pack construction methods, a single failed cell cannot simply be replaced.
Something to be aware of, batteries degrade largely through three modes. Calendar aging, cycle aging and duty aging. This makes it bloody hard to compare any battery like for like based on age/km beyond actually testing the internal resistance on each cell (which is what I believe battery health reports). A 100,000km bike that had only ever AC charged, lived in a garage and pootled around town will be in better condition than one that had DC fast charged at 25kw, been ridden at 200km/h and freeze/melt in the sun. Batteries will degrade regardless of use year on year (calendar aging). Cycle aging is the number of times a battery is discharged/charged, which results in physical changes to the structure of the electrodes and chemical decomposition of the electrolyte. Duty aging is the same process as cycle aging, but more impacted by the charge/discharge rates, physical damage (vibration) and temperateure exposure, with the higher C rates, temperate and vibration exposure accelerating damage to the cells. There is absolutely nothing special about the longevity Telsa battery packs, aside from compared to earlier EVs they used liquid cooling vs air cooling, which maintained pack temperature better. While a telsa NCM battery outperforms a nissan leaf NCM pack which used air cooling, they are likewise vastly faster degrading than a Chevrolet Volt, which has set greater limits on C rates and reserve capacity (After three years Leaf - 94.7%, Tesla S 95.9%, Volt - 98.2%). The lesson here is our air-cooled packs are likely going to be a little worse than a leaf pack...... Having said that, provided a pack hasn't been mistreated, I've anecdotally heard good things about energica honouring replacements. The 3 or 5 year warranty on the energica is actually pretty outstanding in the motorcycle world, most motorcycle manufacturers only offer 1-2 years.
The Telsa warranty sounds good, but isn't actually outstanding. Yeah, its 8 years, but its only 70% health. Lexus is 10 years/80%. Kia/Hyundai do 10 year/70%. Almost all other warranties are 8 years/70%