Firstly, we don't know how close that "right on the horizon" is. I don't think we can infer that the 096 SSBN is already under construction unless there are more solid/concrete proofs/indications.
Next, assuming that the claim is accurate - If those larger SL-ICBM tubes are indeed meant for JL-3, then I believe that the two 094B SSBNs are likely technological validation platforms. The 094/A is a readily-available and operationally-proven platform, thus having the two 094Bs based on them is reasonable. Those 094Bs probably are playing the same role in the SSBN domain as the 093Bs are doing in the SSN domain.
Plus, it also depends on how many nuclear warheads that the PLA CMC plans to put on their SSBNs in the near term. These two 094B SSBNs might just be a marginal expansion of the PLAN's SSBN force through replacing the sole, aging 092 SSBN.
Of course, I'm not against building 096 SSBNs either - In fact, apart from being SSBNs, I do see the avenue where the 096 becomes the platform for special mission and SSGN applications.