I imagine it will probebly be a D/E version of a Los Angeles class or Seawolf class.
That won't be impossible,given America's tech base but it sure will be hard.First of all,D/E subs are a world apart from their nuclear cousins.Speed,size,sensors,armament are all vastly distinct.Tweaking an LA class boat into a D/E is nothing but a disaster as the biggest D/Es today(Australia's Collins class) only weigh about 3,000tonnes & the LAs displace 5,500+t.IT would have big manning problems(for a small navy like Taiwan) & it's size would be a massive impediment in what will essentially be shallow waters.Anyway,if a sub design is finalised,it will take atleast 2-3years to modify & settle for a design & atleast another 4 to build them.Question here is does Taiwan have the time to wait that long??