I will preface that I haven't played anything regarding the kuva liches, but I will leave feedback as to why I won't now and for a little while based on what I have read on the update post and any official info given.
Firstly, the on paper grind to actually fight the lich seems a bit much (considering a later point in which I will mention). First, you need to farm kuva siphons for a chance to get them or a flood to get one of them for sure. Then, you actually need to run the requiem relics to get a chance to get the new mods. Then, you need to farm the lich's minions to find what the weakness is, unless you want to do it by trial and error and potentially waste time.
Now, on it's own it's just a tedious grind towards a boss fight, which isn't awful. What makes it awful is that, while that lich is active, the lich will actively taking your loot on any mission it influences until you take it down, which has been established to be a very long process. Frankly, it feels forced: I either spend a great deal of time trying to kill my lich, or I just let the thing take my loot.
Take this feedback with a grain of salt as, again, I haven't tried it anything lich related and this is strictly on what I see on paper, and just based on what I see I am simply not interested. Progression towards the boss is fun, but making that progression entirely random due to layers of RNG is not. Until things change, any grineer lich larvae that show up I will spare, because I can't be bothered.