Hello and welcome to HCM,
As you described,your root-canal treated lower right side teeth is periodontally affected resulting in abscess
If you are not willing to retain the teeth,it has to be extracted and replaced with fixed prosthesis
The prosthesis will prevent shifting of adjacent teeth.
Regarding your left lower teeth,if it do not have any problem associated,no need to worry.
I Would suggest you to maintain good oral hygiene
accumulation on the affected site.