Lottery with no bloodlines as a draw.all draws are only basic attributes like more chakra, higher regen, higher strength , higher agility(flexibility, reflexes, not neccessarily speed), higher int (memory , IQ), talents (taijutsu, sage arts, chakra natures, combat instincts , weapon master, etc). Only basic chakra natures no wood release etc. Fusion option will be given in future and mc would have to forsake adding another talent/attribute to fuse existing. Its all up to MC choice.
Idea is for MC to build his own bloodline. The way the talent manifests physically varies so essentially MC can build his own sharingan if he wants to. E.g if the talent is to maybe increase bullet time, increase genjutsu talent and the way it manifest is by causing a physical change to the eyes, it is almost like sharingan but the look will differ. All of this is up to the MC. Maybe rather than Gacha this can be a path selection, based on the quest the MC overcomes or achievement that mc gets he will get the corresponding selection to choose to boost his bloodline. mc gets to choose how to build and refine his bloodline.
This story may even carry forward to boruto era showcasing the mc very own matured and new bloodline against the aliens. MC maybe able to choose which child inherit what bloodline abilities