Master Grade 1/100 Series:
More than 80% probability
MG 1/100 Sazabi Ver. Ka
MG 1/100 Gundam Delta Kai
With the big launch of the MG 1/100 Nu Gundam Ver. Ka. We can only hope to see it's rival mobile suit, the Sazabi Ver. Ka to be released, perhaps a release later this year or in 2014. MG 1/100 Gundam Delta Kai is also another high possibility using the part of the Delta Plus mold.
More than 60% probability
MG 1/100 Justice Gundam
MG 1/100 Providence Gundam
MG 1/100 Legend Gundam
MG 1/100 Perfect Strike Gundam
Following the release of the Mobile Suit Gundam SEED Re-mastered Blu-ray box set and the televised remastered version this past year. Not all the mobile suits has seen a Master Grade release yet. Among the 4 listed above, 2 of them are likely to be released. Withe the Re-mastered version of Mobile Suit Gundam Destiny this year, perhaps we will see some new Master Grade release from that series too.
About 40% probability
MG 1/100 Geara Zulu
MG 1/100 Geara Doga
MG 1/100 Jegan
MG 1/100 Loto
MG 1/100 GM II
MG 1/100 Methuss
MG 1/100 Hambrabi
MG 1/100 Asshimar
MG 1/100 Gaplant
Following the upcoming release of the MG 1/100 Jesta. The next Master Grade release for the Gundam UC series could be a Zeon type mobile suit. And we could expect more Master Grade releases from the Mobile Suit Gundam Z series, the previous release from Z is the MG 1/100 Marasai
Perfect Grade 1/60 Series:
PG 1/60 Unicorn Gundam
If the Unicorn Gundam is released in PG Form, it would be a pretty expensive. But it is quite exciting if there ever would be a release for PG Unicorn Gundam or PG Sinanju.
Comments below your upcoming release predictions!!!

(Image of the 1/35 Unicorn Gundam @ Shizouka Hobby Show 2009, image via Gundam Base)