Well then can Bitcoin remain at 50k in the future even with a large number of bitcoin users or will it go down in price with time?
Because now they say a small transfer of say $200 can cost around $30 in transaction fee...so that can't be useful if Bitcoin remains at 50k in the future.

Simple economics subject will definitely able to answer this one out.If we do talk about price then it would always matter in demand and as you mentioned with large number of bitcoin users in upcoming years
then that do simply means that demand is on rise too which means it do increase its price also. Price isnt the solid indication for assuming that fees would be high because it all matters with the network
condition if its congested or not or simply talks that if there are lots of transactions that do happen at the same time which would really result into high fees but if not then
you can able to transfer millions of usd with just paying off less than 1 buck. Isnt that great?