Really? This seems like a VERY questionable strategy. I'd wager that a large number of bass players that play fivers could care less about new 4 string models as a basis for whether they want to buy a five string version. I've been rocking my Mercalli for several years now, and I doubt I'll ever own another bass (except an upright acoustic) that has 4 strings. I'm a big proponent of Reverend, but it's a little frustrating to see that the options are Mercalli and...well...Mercalli for quite a few years now.
Meanwhile, constant color updates and other things going on in the 4 string space. The question I would pose is....are you selling fewer five strings because there is lower demand, or are you selling fewer five-strings because you essentially offer one new model and haven't given us anything to want for several years? In 20 years of bass playing (and all but my first two on five string) it has never occurred to me to play a 4 string version to see if I'd like a five string version, I'll simply go find somebody that offers the product I need. The same reason different guitars with pickup combos, string counts, etc. are suited to different players, it's no different for us in the bass camp.
I guess, IMO, using four-string sales/experience to dictate a product strategy for five-strings seems misguided, as I'd bet there are far more players who play one or the other, rather than both. As a result, it seems your simply ignoring the players who have no interest in playing something without a low B string. Much love to Reverend (did I mention I love my Mercalli, I will NEVER part with it), but if that's an actual product strategy, you should hire a new product manager