I think that the Archbishop may be looking for a way to keep TEC in the Anglican family. There must be a strong possibility that they could be removed altogether! He is laying the groundwork for a policy of:-
  ‘if not full membership then partial’, and
  ‘If not the whole of TEC then the faithful parts’.

http://www.churchoftheword.net

Will TEC accept the two-tiered system, which essentially tells them to
“sit in the back of the bus” ?

A bigger question ... are they being asked to take a secondary role?  It all depends on how one reads what was written.

The logic is that a covenant calling for interdependence and adherence to catholic teaching on marriage (as RDW articulates that here) would not be signed by those wanting to go their own way. No one forces TEC to sit ‘in the back of the bus’; rather, the direction of the bus is one TEC does not wish to go, and so does not board. That is the logic. At issue is then what to do with those who choose the bus and its direction.

#3—they are not being ‘asked’ to take a secondary role. RDW indicates rather that a Communion-catholic direction is probably not one that many Bishops, given what they said at GenConv, will want. The decision will be theirs. From the looks of it, he says, this will mean two tiers, because the vast majority of the Communion lines up behind the teaching on marriage he here articulates. A covenant will only make sense, then, if it speaks as the Communion speaks. If it does this, then given what RDW sees GenConv having done, he concludes that a major block of TEC will resist signing. If a covenant does not meaningfully represent the mind of the Communion, then it will serve no purpose anyway. RDW is observing TEC through the lens of a covenant process that eventually means something and in which section 4 emerges unscathed. In such a scenario, the province of TEC would have difficulty covenanting, given what it has done at GenConv. So there would need to be two tiers. That is the logic. Difficulties exist at the level of sorting this all out. That too is acknowledged. Section 4 is under review and also RDW is not prone to foreclose on anyone changing course. I doubt he does this because he believes such a change is forthcoming, but because he chooses not to foreclose on anything out of a sense of God’s sovereignty and human frailty, including his own.

Except TEC has a track record of agreeing to things and then doing something different.  Based on past behavior it is possible that TEC would sign the Covenant and then ignore it.  We then get back to the problem of enforcement which is something that the AC has proven it cannot do.

And of course it does nothing for people who within TEC.

TEC won’t stand for being placed in any secondary role.