I wondered if the reason Roxy disappeared was to symbol the fact that his desire for sex as part of his social relationships had gone. Just like the junkies dying symbolised him being over a need for drugs (but obviously not alcohol).
And that Brian being so repulsive and explicit was a indication that it’s a mistake to base relationships primarily on sexual needs.
I did like the end scene. I’d thought earlier in the season, when he was out walking the dog after the nurse had found a new partner “uh-oh, he’ll be in trouble when the dog goes”.
So I liked how when he walked off it was just him at the dog. Lisa joined him for a while and disappeared. Then you saw the tree turn to it’s autumnal coat to indicate him entering a new season in his life and then passage of time. Then the dog disappeared and he walked in on his own for a while, seeing memories of Lisa and dog in his habitual routes.
So to me it symbolises him just living out the rest of his life, first with the dog, then in his own. In a place he is familiar with and that holds a lot of memories, with friends and colleagues round him.
And how his continuing love for Lisa inspires those people round him to give love a chance, because how he is shows that live can endure. So his legacy and purpose is not just giving away the money, but also showing people that love die last and can be eternal.
I used to work with someone who worked with him at ULU before he was famous. She said it was impossible to get anything done because he was so funny. David Brent is based on in part someone who used to work at ULU.