LG sell a 77" in the C and W ranges and an 88" in the new Z model. However, Panasonic only use the 55" and 65" panels for their models.
If they see a market for a smaller OLED model, I'm sure they'd go for it. That might not happen until they've managed to analyse LG's sales figures for the 48" model though.
Theres a lot of rumours circling about multiple manufacturers breaking the 55" limit on OLED. While it conceptually appeals, Id be wary of getting in early until we know whether smaller individual OLED pixels were more subject to burn in, or had a shorter life span under heavy testing conditions.