Is F2P dying a slow death?

Yes and no. Every time a new thing is added to the game, you need to look at how it is monetized and how its offered for free. You can make a very good argument that the Sith raid was a huge blow to most f2p players, not so much so that the content was hard but more so that the devs have ignored and basically continue to ignore people who are doing tiers 1-6. They put all their time and energy in improving hSTR and nerfing characters/strategies as apposed to fixing 1-6 rewards, health pool, and RNG. The fact there proposed "fixes" haven't come yet is yet another put down to the f2p population. Now when it comes to slicing mods, there was alot of good for f2p players. Mod energy with 50 crystal recharge is huge, and slicing materials are actually pretty easy to farm and getting all your arena mods up to yellow shouldn't be too difficult. However they essentially put the gold slicing material needed to take a mod from 5 to 6 dots behind a paywall and if you want it free to play you have to farm them out of the Guild Store at the expense of farming characters/gear. Its 3150 tokens to slice 1 mod and this is coming at a time where the vaste majority of the playing population is still trying to gear all their hSTR teams. What you are going to see is people struggling to get their current arena mods up to 6 dots and that isn't taking into account when someone gets a new arena mod that they then need to focus on slicing up.

I personally being the devs should not be trying to monetize mods period. One of the best moves they ever made was making mods in the mod store purchasable with credits as apposed to gems. Mods just play too big of a role in the pvp for them to make them so hard to farm for f2p players and a better store to put those gold slicing materials in would have been the arena store.