Our son was forced to try something similar when we moved to the Bay Area. Our movers accidentally put his box of toys into storage. So for the first few months he played with only a subset of his toys. When he got his toys back from storage he did enjoy them more than I expected. Maybe it was because they were in storage for so long or maybe it was because he was now a couple months older.
When our son was younger, I tried making his toys more interesting by organizing them around themes. One day I would get out his farm toys and books. Another day I took out his car books and toys. It worked very well...until he became a toddler.
As a toddler, our son became interested in taking more control of his playtime...which toys to play with and how to play with them. I quickly realized that one of the best ways to let him direct his own play was to teach him where all of his toys were stored. And to keep the ones that he typically plays with easily accessible. That way he can choose the toys that most interest him that day and decide how to play with them himself. Shouldn't he be in charge of his play, not me?
I still bring out some of the lesser-used toys to play with on a rainy day, for playdates or just because. But, for the most part, it's fun to step back and let him get absorbed into his play. Maybe our organization of toys will change again as he gets older or as his sister accumulates more toys. But for now, it works well for us.
Now that we are in the season of more and more and more toys, how do you deal with their abundance?