When I look at people talking about SC2 I constantly see people talking about it as though it is SCBW with some changes.
I think we have every reason to believe the matchups are going to basically be from scratch. Think back, first, to the matchups of SCBW:
PvP -- optional zeal (depending on map) to goon to reav or temp before or after expo
PvT -- wallin get a tank and mines or siege, and/or N rines and/or CC vs straight to goon, obs, etc.
PvZ -- photon expo or zealot rush vs 2nd hatch ling pump until you can tech, muta harass or lurk contain, hydras vs zeal with storm or whatever, optional sair...
TvT -- get a line of tanks as close to them as possible, get an expo up, keep defending and expoing, scan a lot and drop wherever vulnerable while expanding constantly
TvZ -- m&m pressure vs sunkens, lurk or muta comes to harass while zerg gets more bases. terran might expand earlier. details.
ZvZ -- lings and mutas. maybe get an expo in the case where neither should attack. all-in vs the expo, or vs the spire, etc. etc.
Whether my descriptions are outdated or just plain noob and wrong, that is not really the point. Take the right descriptions of each matchup. They are created by the way the units of each race, the tech trees and build times, all line up together, combined with the travel times provided on each map. The stats, the abilities available, all create these trees of possible events in which all strategies for the matchup lay.
People talk about an SC2 feature as though it is going to effect SCBW TvP, for instance. IMO this is just plain wrong because the matchups in SC2 are going to be as fresh and new as War3's were, as BW's were for SC Vanilla, etc. etc.
One reason is that SC2 has changed the armor and unit types system and the stats of almost every unit, not to mention how they move and fire, not to mention available upgrades and abilities and how powerful they actually are. Basic buildings have new build times, new health, and the maps will be new too.
Right now the game is unbalanced. Will they balance it in a way that creates similar, familiar tensions of SCBW's corresponding matchups? Obviously not. No more than War3's Human vs Orc was at all like War2. With so much change it is going to have to be a completely new matchup.
Another thing to point out is Blizz's reluctance to change things that effect their already-made Single Player. They acknowledged at some point that certain BW units should have been weaker, but they would not change them because they would have to modify the campaign, which they wouldn't or couldn't do. They are currently, designing a campaign around the units they have made. So they are going to be reluctant at some point to make certain changes. This doesn't mean we aren't going to get what we want but it means that there will be arbitrary, new things that they will want to have in place, making it impossible for SC2's matchups to be made to fit the corresponding SCBW matchups, even if they wanted to. If a certain level requires such and such, then they will keep it such and such, meaning the SC2 matchups will have to achieve balance another way--a new way, which means, if any such cases exist at all, SC2 will have new, unfamiliar matchups and not the ones from SCBW that people are basing their theorycrafting off of.
So for all our theorycraft purposes, if you agree with me, the matchups in SC2 could all be akin to SCBW's ZvZ, or TvZ, for all we know. It might play out that way. SC2's TvP might be more like SCBW's PvP. Who really knows? So worrying about the macro phase of TvP or PvZ, is partially moot because we don't know how important, if at all, that feature will be in any of the new matchups of SC2.
Take for instance, all this talk about MBS. MBS would not "ruin" every matchup of SCBW, only certain ones, for the current balance and maps we have come to accept as standard (these weren't created by Blizz in the slightest, either). For all we know, SC2 might be better with MBS, might not. Might not matter either way.