It all depends on what Spain decide to do. In the no-deal law it said that the TIE could be for up to five years - provided the UK reciprocated, which didn't happen.
All we can do is wait until the Spanish authorities publish the requirements and procedure.
The worst-case scenario is 1/2/5 year renewals with a need to prove finances on each of the renewals.
The best-case scenario is a 5 year TIE from the outset.