Difference TPA3116 and TPA3116D2

The suffix D2 I think just means class D, 2 channel. There is no TPA3116, the base part number is TPA3116D2. Some people strip off the end thinking its a packaging option, and the device marking on some chips in the series omits the D2 too (see the packaging info section of the datasheet).
For instance one full part number with packaging is TPA3116D2DADR, the DAD being the package, the R being for "reel".
I guess they reserve the right to come out with a TPA3116D4 in the future for instance.