I think you would have to look at what percentage of the PS3 user base has 20 GB PS3 systems versus the 40, 80, 120, 160, and 250 GB systems. If the proportion of 20 GB users is large, then they might consider it, however if the majority of users are sporting 40 gb+, they'll probably just release the software as that will cost them less and increase initial profit margins. I would guess that 20 GB models probably make up a minority of the market relative to the rest, and as such would not warrant an "extra hd". There might also be an opportunity to purchase a FF14 Collector's Edition PS3, as they did that with FF13 on the XBox if you are concerned about your PS3's storage capability.
WoW Blackhand-US-Date of Retirement: 9/21/2010... /Sigh
Devari - 90 Rogue 85 DK Druid/Mage/Warrior 70+
FFXI - Shiva "Retired.... Or not? One more try, honest."
Desmar - 65 Sam 36 Mnk 18 Thf 12 War
FFXIV - Devari Garamond - Sargatanas 50 Paladin / Culinarian / Weaver / Armorer
Beta - Devaria Ariadne - Ultros - Pugilist