潤う: fields moistened by rain and shops' prospects
Compare dry fields receiving rain with village shops' prospects in 潤う. Preserve the tourist-increase condition and prediction rather than reporting actual visitor growth, higher sales, or complete recovery.
Rain moistens the dry fields
潤う (うるおう) can describe becoming moist. 「久しぶりの雨で乾いた畑が潤う。」 means “The first rain in a long time moistens the dry fields.” 乾いた畑 names what receives moisture, and 久しぶりの雨で gives the cause.
The present 潤う expresses the relationship between the rain and the fields becoming moist. It does not report that every crop has recovered or that harvests have increased. Read the moisture through the specific pairing of rain and dry fields.
Shops may prosper if more tourists come
「観光客が増えると、町の商店も潤うだろう。」 means “If more tourists come, the village shops will likely prosper.” The shops' 潤う concerns economic prosperity rather than being wet. 観光客が増えると supplies the condition under which that prospect is presented.
だろう marks a prediction about what may follow. The sentence does not report that visitor numbers have already risen or that shops have achieved higher sales. Keep the increase in tourists as a condition and the shops' prosperity as a prospect.
Separate the fields' cause from the shops' condition
Rain is the stated cause of moisture in the dry fields. More tourists are the condition attached to the shops' economic prospects. Identifying the subject of 潤う and the cause or condition before it helps distinguish moisture from prosperity.
The scope of the outcomes also differs. Do not turn the fields' present description into recovery from every kind of damage, or the shops' prediction into recorded sales growth. Even though も adds that the shops will benefit too, it does not remove the uncertainty expressed by だろう.
What causes the fields to become moist, and what condition is attached to the shops' prospects in the two 潤う examples?
Show the answer and why
Rain after a long interval is the fields' stated cause. More tourists are the condition for the shops, and だろう keeps their prosperity as a prediction rather than an achieved result.