If I am correct, that's a Rose of Sharon - Althea, not Hibiscus, although in the same family - and yes, that's what color the blue ones are.

Well, a Rose of Sharon is a Hibiscus, but all Hibiscus are not necessarily Rose of Sharons, if you know what I mean. Rose of Sharon is just one of the common names for Hibiscus syriacus. There are lots of other Hibiscus varieties that wouldn't be called Rose of Sharon, like the more tropical ones that most of us are used to calling Hibiscus as a general name. I agree with the assessment of it being a Rose of Sharon, definitely! This is the typical scenario of blue that is really lavender/purple. Gotta love that!