The only reason i see this kind of remake/remaster would be to spread it worldwide.
The 1st one has not been released in Europe and I have not seen any add either. I don't think it did good sales, like most of JRPG that has not FF, tales of or DQ in their name ;-;
But it had really good review from the few people that played the game.
Editor/Distributor has maybe seen a market if they do a correct advertising campaign. Look Fire Emblem, it was about to die and now it's not dead for while.
Also I think they have the will to provide their game again because they think is was good (and they are right).
About the new Radiant Historia incomming, from what i have seen in trailers, it's not that different from the original. I expected a better visual changes. But i can't say anything for the content.
I would advice to way for a possible announcement, at least until the Japaneses release. I see no doubt that the new RH would be better that the previous one, but i don't see any benefit by playing in Japanese (except if you can read it)