I would hope they can make pre-sentients a bit more common in 1.5, I can't even remember the last time I actually found ones in game, possible they should change the mechanic for them appearing and have them as common as Primitive Civs, or better yet, have the current spawn rate for Primitive Civs, but shift half of it to Pre-Sentients.
Logically it makes sense for it too be more likely to find Pre-Sentients, who may be Pre-Sentient for Millions of years, versus a Primitive Civ that might be in the Bronze age for Thousands or Atomic Age for decades.
Though it would be nice to see additional genetic engineering perks with the biological ascension, but we don't know what the full details will be.