TLC will provide ultimately a 33% reduction in cost per die area versus MLC. I'm looking for a 20x reduction.
Nobody is using TLC right now, despite it being available. Compared to MLC, reliability issues rise exponentially, and shelf life is as low as four years, and this will get worse as we go smaller, because the cells will be more leaky. All that for 33% improvement.
If nobody's using TLC right now, there wouldn't be a price for that, no? Actually, a lot of cheap MP3 players and mobile phones do use TLC flash. OCZ once wanted to use TLC for SSD, but that proved to be difficult, because TLC is not good at erase.
The paper about "bleak future" of NAND flash is about using them as SSD (and yes, I read that paper before). If your usage pattern is mostly read with occasional write (as, for example, a game cart), even TLC is fine.
About the cost, remember that feature size is only part of the question. Fabs are pushing for 18" wafers too. It will roughly half the cost (compared to current 12" wafers). Also, there are also other possibilities of improvements in manufacturing efficiency.
Then if you look at optical storage, I have to say that I don't know if we are ever going to see maybe a few more generations. Right now, Blu-ray is completely fine (and enough) for most movie needs. Computer storage-wise, Blu-ray is not wide spread. Blu-ray burners are not selling very well, nor BD-R discs. Although I wouldn't say that Blu-ray is the last generation of a consumer optical storage format, I think we are not far from the last. So actually if you look into maybe a decade later, solid storage is probably going to be more popular and cheaper than optical storage (and of course IMHO internet distribution is going to be mainstream at that time).