Not really. The problem for any GOP candidate is, that HC will do incredible well with centrist voters. Heck, she´d beat most republicans in a race for their own centrist voters. She also has the backing of the democratic establishment and big interest groups. Any progressive candidate could rip her a new one on the left side, but she runs unopposed because of her name/connections/personality, so she doesn’t alienate any of those voters. HC will beat any rep. candidate in the middle while she´ll also gain votes from the progressive left-wing. On the other side any rep. candidate will struggle with her appeal to centrist voters, while also being attacked from the far right.
Centrist voters aren't all the same.
There are centrist voters in states like Ohio, Virginia and North Carolina (Hillary can forget about Florida) who will view HRC as an ideological liberal and other centrist voters who will like her and other centrist voters will remember her vote in support of the Iraq War and view her with distrust. It's way too early for a firm prediction as there is actually a campaign that has to be run first, but Hillary has work to do to fire up the "left-wing base" as well as reassure the "centrist voters" who may be Dem or non-party affiliated independent that she's not a lefty. It can be done, but it's a tightrope walk for her.
On the Rep side, it's either Bush or Rubio, full stop. But let's forget about Rubio for now and assume Bush.
JB's immediate problem is somewhat similar to HRC's: firing up the frothing base of the party while reassuring centrist voters that he's not really a frothing wingnut. JB is more naturally a "centrist" politician, as he has nowhere near the ideological baggage that HRC has, which is why he has a problem with the right-wing in his party in the first place. His "baggage" is guilt by association with GHWB and W, but in the end voters vote for the candidate, not the family of the candidate. Even so, Hillary is no position to berate Jeb about his family association.
If it's HRC v JB, which is very likely, the question is whether each candidate makes a run for the base or a run for the center. It's way too early to say, but I suspect they'll actually make a run for their party bases. As most of you know, our potus election is actually decided by the electoral college (gotta get that t-shirt someday!), which means only a few states are in serious play (running up the score in California doesn't help Hillary). Someone put up a good website last night and it maps it out fairly well. But you actually have to drill further down into those swing states to determine whether -- to take Ohio for one example, from a JB perspective -- you try to eat into the centrist vote in the suburbs of Cleveland or maximize the base vote in Cincinnati and Columbus. On some level you try to do both, but the mega-narrative of the campaign message will be either a pitch to centrists or a pitch to the base -- on both sides. You can't really do both. You pick off micro-pockets of voters here and there in a few key states but what may well decide the winner in the key states is whether Hillary can replicate of the Obama base vote in cities like Cleveland in Ohio, Alexandria and Richmond in Virginia and Charlotte and The Triangle (a geographic place, actually) or whether Jeb can maximize the incredible base vote he picked up in the smaller towns of those three states. It's not just those three states, but whoever picks up Ohio, Virginia and North Carolina (JB wins Florida) gets to ride around in Marine One all he or she wants for the next four years, probably eight.
For those of you on the "Hillary is inevitable" bandwagon, you might want to take another look at her dreadful performance in front of the cameras at the UN a few weeks ago. She'll no doubt polish things up, but we've seen nothing from her for a very long time that suggests that fit and in form for a magisterial potus run.
