At Laracon online yesterday, I think Taylor said there was quite a bit of changes coming in Spark 6.0. Enough to warrant a new major release. He also said that any Spark licenses for 5.0, would be given a 50% discount to upgrade to 6.0.
That would be $49.50 for single site, and $149.50 for multi-site licenses.
To me that's not too bad to pay for about 12-24 months of of updates...especially considering that Spark should be being used on a SaaS that should be generating income. Not to mention, you do not have to upgrade. You can continue to use the 5.0 version as long as you want. Not sure I understand the problem.