Let's see... the asciens learned that those with the echo could not be tempered
2.2 they learned that mythological figures can be summoned as primals
2.3 had somebody be given the echo but was subsequently absorbed by said primal
2.4 had a Hydelyn-given echo user maintain her will while being a "vessel" for said primal.

Lore-wise I say its possible for us/ other echo users to be vessels of primals. And with the introduction of Auricite then perhaps it won't be a burden on the land