Roughly how much fuel and ammunition would say a PRC armored division need per day of operations? How many transports would have to cross each day just to keep it firing and moving? There would be no second echelon behind it so how deep would it be able to go? Without reliable supply (which seems impossible given that the USN would probably get involved) any invasion force would just turn into a bargaining chip for the ROC during the post conflict negotiations. One more thing, suitable landing areas for a massive amphibious assault have probably already been anticipated, probably scheduled for mining or something like that in the event of conflict.
I'm no staff officer, but my point is that at this point in time an ROC vs PRC conflict (sparked by an independence declaration for example) would more likely take the form of a punitive raid rather than an outright invasion. For all their threats the PLA knows that the most it can do (short of nuking taipei) would be to hit ports and cities in order to cripple Taiwan's economy and to turn public opinion against a pro independence geovernment. Perhaps when the PLA can credibly control the straits, the threat of direct invasion may be truly taken seriously, but by then, I'd wager, MBT's bought today would be obsolete anyway.