Welcome. We also have an "Introduce Yourself Here" thread, a good place to stamp your introduction and what not.
Nico was Frank Williams' Lewis.
A different relationship, but Williams gave Nico his chance to shine, and Nico committed himself to the team as a thank you. It was all handled very well, and now that he is established, the relationship has come to it's logical conclusion. Nico is moving on to a team where he has a better chance of a championship.
I think Nico was confined by the Williams. His ability to run out and set the quickest lap of Friday practice so many times this year confirms his pace, and the cars peaky one lap pace. Even though the car was basically empty, it is still not an easy task to accomplish. Ask his team mate
With either testing or money, Williams would be able to have a chance to shine again. Without testing they can't develop the car in a traditional way, and without money they can't develop in the virtual world as well as other teams.
He will always likely have a warm seat there if he wants to ever return.
Regardless, Rubens is a good choice, as he proved he still has a lot of pace, and his experience in Ferrari and now BrHawnda isn't easily overlooked.