SAFE and blockchains are orthogonal, not opposing, technologies. Yes, they both can be used to facilitate money exchange, but not all of their use cases overlap. I believe they both will live on, probably in a symbiotic relationship, complementing each other.
For example, compared to the “copy everything” method used today, SAFE is an obviously superior storage place for the blocks of a blockchain; no need to store the whole chain on your drive anymore.
Blockchains (trees, etc) are awesome at enforcing a concept of ordinality between events, which is something a stateless network like SAFE (without the Data Chains) could not easily do (though I have an idea to introduce some network-wide state, for when it’s desirable.)