I genuinely think this is unlikely. For these two strike days, the NEU has agreed special dispensation for teachers to go in and support Y11/13, and so the impact on secondary schools will be reduced. That doesn't mean it'll be reduced on future strike days.
Equally, in my area, we have more primary teachers on strike than before, we have more pickets at primary schools than before, and it's primary school closures that have the real economic impact.
More people voted against the pay offer (and a higher percentage) than in the NEU indicative ballot in the autumn. Plus ASCL and NASUWT are planning to reballot. If they are successful, (And I hope NASUWT have learnt from their mistakes last time around) then it's very likely we will see a lot more full school closures in the autumn term.
If NASUWT are coming out too, it will reinvigorate NEU strikes, as well.
The Tories hope this is all going to go away quietly, but it's not.
They didn't want to negotiate before, but NEU strikes alone brought them to the table. If ASCL and NASUWT strike too, then the government will have no choice but to negotiate again.