Besides the main argument still holds true, if you think at how the BSD license works. A fork can be continued with a different license, but the work accumulated in 15 years remains BSD, so it's not like a relicensing where the previous contributions cease to exist in that given license.
But everybody (Redis Inc. included) can continue a fork with a different license, or with the same license but with different development ideas, and so forth. BSD one-o-one.
To me the most interesting thing for the future is what new ideas caching systems can bring us. When I left Redis I was very interested in protocols where clients had a play at the party more interesting than just querying the DB. These ideas driven the client-side caching feature, but I had a lot more developments about it, that was not able to implement for time concerns (and since I left).
Other interesting ideas are around clustering. There is Redis Cluster, then at some point I had a friend working on a proxy to abstract cluster away for the clients, but there are other interesting things that can be done just with advanced clients that are VERY resistant and reliable in practice. Think at Twitter: they used to write to N nodes with their own algorithm even if nodes had persistence enabled.
And what about data structures? Streams were quite an interesting idea, but there is more. And there is also the possibility of playing with Redis-alike systems that offer more radical ideas and changes to the data model.
To me, all this is a lot more intresting than SSPL vs BSD.
What did you buy the last time you paid for software? I bought a license for FontCreator, from High-Logic. There is a long list of softwares I would be willing to pay some amount of money for, as a lone developer, but I most certainly can't afford the enterprise deals.
An argument can be made that somebody betrays trust when they say BSD and a few years later it turns into something else.
Conversely, there is this idea of "making a market": putting facilities in place for the exchange of goods, and signaling that there is a demand for those goods. The last part is important. If we as software developers and hackers use every opportunity we have to signal that the highest amount we are willing to pay is $0.00, then many businesses will close shop, move to Enterprise Uptown, or both. Or they will use bait-and-switch, a-la Redis, which is definitely scummy.
