As you say, Dave, we are all different. I'm a tax resident, spending over 6 months a year there.
I pay tax in the UK on my naval & local authority pensions, but my private pensions, UK state pension & investment incomes are taxed in Spain. I have personal allowances in the UK, whilst in Spain, I claim my personal allowance together with my wife's, who is not resident.
I have no clue what will happen future tense, & like everyone else will just have to wait & see.
The bottom line is that Spain needs Brit spending as well as tax from residents. I can't see them prejudicing either.