I think you may need to re-read it, johnzx. It says the rights that UK citizens already have will be retained if they are, resident in Spain or have applied for residency before the end of the transition period which is 21 months after Brexit day.
(b) United Kingdom nationals who exercised their right to reside in a Member State in accordance with Union law before the end of the transition period and continue to reside there thereafter; (It also refers to family members, those who work and several other categories)
2. Persons falling under points (a) and (b) of Article 3(2) of Directive 2004/38/EC whose residence was facilitated by the host State in accordance with its national legislation before the end of the transition period in accordance with Article 3(2) of Directive 2004/38/EC shall retain their right of residence in the host State in accordance with this part provided they continue to reside in the host state thereafter.
It then goes on to say that you would retain these rights during absences from the host nation unless the period of absence is a continued 5 years.
The 5 year rule would probably only come into play for those applying for residency after the transition period has ended which would make sense as we will not longer be a EU country.
And you need to update your residency requirements. The amount required for EU citizens is nearer €10,000 a year now.
Of course, the above would only apply if the draft treaty is agreed by our parliament and those of the other 27 nations which is looking rather unlikely if you've been watching the BBC news today.