The CS210 is the baby unit of the Nimble range - however it does have scalability. You can take the SSDs up to an X4 (4x 160GB SSDs) for a total of 640GB SSD cache. You can also add a single capacity expansion shelf should you wish. You cannot replace the controller to a larger model due to the difference in RAID set and stripe size with that system (8 disks vs 12 disks in every other system).
You can also scale-out and cluster the CS210 with any of the newest generation All Flash or Adaptive Flash arrays should you feel that would be a better option. You would need to be on NimbleOS 3.x to be able to cluster with the new arrays.
My recommendation would be to check out Infosight and look at the performance of the CPU and Cache of the array, and then to speak with your local Nimble SE to see what would be the best way to proceed.