Yes, it's OK. It sounds as if you are making a list of things that will be better in the future. There are no rules, but it can be effective rhetoric to repeat the same grammatical structure several times. "In stores, everything will be cheaper. On streets, there will be more trees" works well. For an example of this, consider a famous passage from a speech by Winston Churchill: "We shall fight in France, we shall fight on the seas and oceans, we shall fight with growing confidence and growing strength in the air, we shall defend our island, whatever the cost may be. We shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender."

There will be more trees (standing) along the sides of streets.

It should be