i have several suggestions to prevent people from getting bored of the game.
1. increasing of lvl limit. almost every game does it overtime so y not settlers? even like 10 lvls every year would be better than forever sitting on lvl 50(reasons for this explained in the next point).
2. star coins at lvl 50. i mean seriously 1 gem package a week? even casual players can get 600 star coins a week. 900 star coins for a premium? turn on premium and recoup that in a day. apart from these 2 u probably wun buy anything else with star coins. so eventually u'll be back to where u started before star coins when u no longer get xp from adventures once u hit lvl 50 where it becomes pointless to do adventures. so instead of 1 gem package a week at 600 coins y not make it 1.5k or even 2k coins but make it unlimited. at least this will give people some motivation to farm for the coins and at the same time it will also give people who can't afford to buy gems using $$ to get gems for stuff that can't be gifted like vet and so on.
3. star coin shop: another way to make farming for star coins worthwhile is adding stuff like watermills and so on. maybe 1 or 2 per mth. that way it would be easier for people to get them instead of saving like a mth through 200 gems a week to get 1 watermill.
4. new stuff: u think u're adding new stuff but in truth u're only improving on wat u already have. the core of the game still remains the same and eventually people will get bored of it. increase the lvl limit while adding new stuff like new buildings resources and so on. give people something new to do
P.S: feel free to comment on my points or add on to them. this is wat i think and i know not everyone will agree with them.