Who knows. Shou certainly knows how to write yuri, but after 4 volumes, there's no romance in sight, whether it's het or not.
Still there's unresolved issues that he touches from time to time like Keiko's nightmares, her relationship with her mother, Ran's obvious attraction to Keiko (remember how she made soba, that her mother said she should do for her "special someone", or the honmei choco..), etc..
Considering the success of Stretch on the BGS site, I don't think Shou is in any hurry to make a conclusion. The start of a romantic relationship between Ran and Keiko would look like a End Flag.
Still I think they are aware that the popularity will fade if nothing happens, so I still hold some hope.