The phylogenetic definition of the clade Dinosauria
As of right now it is still the same, the evidence for sauropodomorpha being a outgroup is not statistically more reliable, this may change, however this will still not have much impact. There are several ways in which dinosauria is defined. 

The most recent common ancestor of Megalosaurus and Iguanodon is also sometimes used since they were the original animals used to define the group. 

The last common ancestor of Triceratops horridus, Passer domesticus, Diplodocus carnegii, and all of its descendants is also used just because of Baron's work.

Finally there are several unambiguous synapomorphies used to define the group, including such things as ankle structure. A full list can be found here.  

In a group as well known as dinosaurs, a discovery like Baron's (if it holds up) is just going to lead to a change in the definition.