I'm hoping we receive either another 25 infamy levels or 75 to round it off to 50 or 100. And I've had a couple ideas how to make new infamy levels fun and worthwhile.

perk deck optimization

I think optimization with perk decks would be greatly interesting toward the game mechanics. Like unlocking infamy levels unlocks certain perk deck boosts which can be mixed and matched to create a separate perk deck.

For example infamy 26 unlocks the "+5% dodge" perk skill for tier 1, infamy 27 unlocks "+10% armor" perk for tier 1, infamy 41 unlocks something like "Damaging an enemy now heals 2 life points every 0.5 seconds for 5 seconds. You gain 20% more health" perk for tier 3.

Then after obtaining a final 9th tier perk (around level 70s) you can create a perk deck mixing and matching tier 1, 3, 5, 7, 9 perks (only 1 tier 1, 1 tier 3, etc....). Then keep the balance the same as perk decks currently are roughly so you cannot receive more dodge than rogue, more armor than armorer, more health than muscle, etc....

tier 7

I've always been a fan of Goldfarb's conceptual tier 7 skills and believe implementing those with infamy levels similar to the first tier of infamy (1.0 mastermind, enforcer, tech, and ghost) could be received well.

I don't necessarily think one should be required to be 25-100 or higher to use said tier 7 skills however. I think you should be able to use an infamy point (even of receiced after level 100, V-100, or even 24-100) and place it in the mastermind, enforcer, tech, ghost, or fugitive tree. Once placed it unlocks the tier 7, which is a unique skill for each tree.

Tier 7 skills would be limited to 1 per build, and some ideas are Bulldozer Armor, X2 primary weapons (replaced secondary), ability to convert specials, shield piercing sentry, and an ability to use 3rd weapon (like PDTH, but more limited to a pool of certain weapons to not break balance).

optimization

further optimization like another 10% skill point reduction in set skill tree similar to infamy 1.0

higher difficulty

Access to a greater difficulty level (infamy 30 unlocks Bain's Contracts for the infamous Deathwish difficulty, infamy 35 unlocks Vlad's contracts, etc...)