When knife, spear, and arrow are used in battle field, The heavy armor is useful. When bullet can go through heavy armor, nobody wear heavy armor any more. But if that heavy armor can stop bullet, It will exist forever.
If a Taiji master can go to UFC and beat up everybody, Taiji will not die out. One good Taiji fighter is all we need.
Your best chances had already past, 25 years ago in UFC 1, 2 and maybe 3....when all techniques, including the anti-rape ones, could have been used and not get DQ'ed.
Now, the UFC is a multi billion dollar business. Your Taiji master in a small, converted warehouse space dojo is going up against fine tuned athletes with tens to hundreds of thousands of dollars in resources (at the highest levels) spent to get them ready for each fight.....ranging from nutritionists, sports meds/docs, top of the line equipment, well paid sparring partners (w/some that mimics the exact opponent), etc.