The impossibility of earning back powered down STEEM by blogging goes for everyone. Including you and me.

It took you a year to earn all the STEEM you have. It takes 13 weeks to power everything down.

But if you mean earning STEEM in the future. Yes, this will be harder and harder. The reward-pool is fixed and more and more people are joining the platform. There is simple less and less STEEM to go around. It doesn't mean that the payouts will go down, they can easily go up when the STEEM price increases.