Reliable data miner TezFunz claimed that Rockstar Games planned to release remasters of GTA 4 and Red Dead Redemption, but abandoned this idea later.
As per a reliable source with clear accuracy on Rockstar plans,
remasters of GTA IV & RDR1 were on the table a few years ago,
but Rockstar chose not to proceed with the projects in mind.
The poor reception of the Trilogy DE might be a reason behind
that decision.
— TezFunz, dataminer
TezFunz also said that Rockstar still doing bug fixes for Trilogy DE and it's slowing down as focus increases on GTA 6.