I doubt that desire for cultural differentiation is going to change much about the diglossic situation in Taiwan, since the continued use of Traditional Chinese characters is already a pretty big differentiator. The government is making some effort to promote the Tai-lô writing system (e.g. https://tailo.moe.edu.tw/index.php ), but overall there's very little incentive for Hokkien speakers to become literate in it. If you look at Wikipedia visits from Taiwan, 92% go to the Mandarin version, 6% to English, 1% to Japanese, and Hokkien is in the tail of small languages behind even Cantonese and Classical Chinese. Of these, I think English is most likely to grow in the future.

Also, the differentiation potential is somewhat limited due to the fact that the majority of Hokkien speakers lives in Fujian province on the mainland (Hokkien = Fujian) and there's some preservation work going on there as well. E.g. Xiamen University's Speech Lab had a working demo of spoken-Hokkien-to-written-Mandarin translation in 2018, although the link shortener they used has since suffered from link rot. https://speech.xmu.edu.cn/2018/1215/c18169a359542/page.htm