I've heard the easily replaceable hash board before (including from Bitmain) and it never quite works out the way you think it will. Have a look between the generations and try and work out how many Bitmain generations are a. board compatible and b. heatsink compatible and that'll give you an answer as to the sustainability.
I think there is a good reason to "standardize" hash boards, but it needs a lot of standards to be followed by all manufacturers. Here are my simple points why universal PCB can't work.
1) different power density. Just compare KnC or Spondoolies chips with BF, Bitmain or others. Two different ways of power density. SFARDS just in the middle. Different power density needs different PCB design and different heatsink design.
2) string design. It is already required, but not all designs are so simple. Bitmain S7 and S9 are hybrid string designs which needs separate buck controller (not necessary when changing design). BF250NM is already prepared for string design, but it is not so easy with BM1384.
3) total output power. It is based on power density. We can see extremely increasing power density with the same case size in Bitmain's products beginning from Antminer S1 to Antminer S7 or S9. One single heatsink can't handle 700W on multiple chips. Even 300W is too much as we seen on S5 failure rate.
It can be win for customer, but it makes so many design rules for manufacturers that it is nearly impossible to implant any standards.
I am happy that anybody spend time thinking about it, but there is still not enough manufacurer competition to do it.