“越来越欣欣向荣”可以翻译为“becoming increasingly prosperous and thriving” 或者 “flourishing more and more”。
“prosperous and thriving”强调繁荣昌盛、兴旺发达的状态；“flourish”本身就有“繁荣、兴盛”之意 ，“flourishing more and more” 也直观地传达出不断向好的发展趋势。
例句：
With the implementation of new policies, the local economy is becoming increasingly prosperous and thriving.
随着新政策的实施，当地经济越来越欣欣向荣。
The small business has been flourishing more and more since it adopted the new marketing strategy.
自从采用新的营销策略后，这家小企业越来越欣欣向荣。