Samurai is only the 18th Power Rangers season right? We shouldn't expect another reunion/crossover until the 20th I reckon, yes? Or do they go with the Sentai anniversaries?
The only crossover that I remember very well was Forever Red, it was the 10th PR Anniversary and 25th Sentai.
I think they'd probably go by number of years, not number of seasons.
Actually there's usually a crossover with the previous year's team on an annual basis, reflecting a Sentai tradition. Though I doubt that will happen on Samurai
, since RPM was not only from different producers but was set in the future.