Yes, in most equivalency sports, athletics scholarships are a year-to-year affair. Reports are starting to emerge (mostly from soccer) of multi-year agreements being used, but those are generally reserved for non-equivalency sports (football, basketball).
In my sons verbal agreement, it was made abundantly clear that it is a four year deal!The only way the scholarship would change would be due to academic failure or not showing up to practice etc. Not based on performance. It was said that the scholarship can only increase if he does really well. I should also point out that at some of the other schools we made visits to, and considered, the scholarship would be revaluated each year.
As we stated, multi-year agreements are starting to emerge and are not the rule in equivalency sports, but the exception at this time.