They've already rejected 1 & 2, unfortunately. Visual novels have a tough time getting to the states; we're lucky we got V.
As you said, the English-speaking VN fandom is still pretty small. There are a few companies that professionally translate titles, mostly for PC, though each of them have a less-than-positive legacy (few if any non-porn games, few attempts to reach new audiences, lots of low quality translations). There are people and groups that create their own visual novels in English, and a few who release them as commercial indie games... though except for The Chaos Gateway, no one has managed to publish on consoles. Also in fandom, there's fan translators, and a few people who only play untranslated games.
That said, it's tough to be optimistic about the future of Sakura Wars, for the following reasons:
1 - Apparently only a few people bought the English version of the fifth game.
2 - The fourth game in the series is not well regarded. RPGFan's review of the untranslated version of Sakura Wars 5 regards the game as a return to form, which is kind of a backhanded compliment.
3 - The original two games in the series have been ported to a bunch of platforms, but the only translations are Russian and Chinese (see this VNDB entry: http://vndb.org/v952 ), and I don't know if the games have aged well.
4 - Things aren't looking all that great for SEGA. Back in the Saturn-Dreamcast era, the company created a few VNs based on series. But the company's only VN in the last four years was Imabikisou, a horror story, created along with Chunsoft.
5 - Red Entertainment seems to be struggling as well -- some of its recent high profile games include Nostalgia and Fossil Fighters. That said, the company also released an otome game equivalent of Sakura Wars, called Scarred Rider Zechs (see this blog entry: http://lijaka.com/blog/2010/03/scared-rider-xechs ), though it's only on PS2 at the moment.
That said, I don't expect any more Sakura Wars games in English, unless someone fan translates the Windows versions, or unless someone creates a fangame.