I'd rather see any of the spin-offs go before the original L&O. I like all the current characters...I hope they all come back for the next season.
Not all of them are...
Also the 21st season next year is supposed to be the finale, for real... really.
Also I think this season's has been the best in years. The cancer storyline, we see her husband and everything clicks well and are more interactions between the cops and the lawyers.