The successor to the 335 series is codenamed "Villa Crest", these are also 2.5" SATA 6Gbps and they will arrive in Q2 2012, around the same time as Intel is anticipated to launch the new 500-series "Sierra Star" SSDs. Both models will continue to use 20nm MLC flash memory.
A few quarter later, in Q2 2013 you can expect to see the next generation drive simply codenamed Villa Crest that will replace the 335 series SSD drives. Intel is not ready to reveal its capacities but a range between 80GB and 240GB would be most likely to show up since these are the sizes that currently sell the most.