I just really started looking at this within the half hour and I don't consider myself to be extremely knowledgeable with tropical so my thoughts should be taken with a grain of salt.
Typically you'd like to see a trough sliding or amplifying moving across the Ohio Valley as a means to capture a storm and bring it up the coast. However, in this scenario, given Henri's latitude and the synoptic pattern I don't think that would be necessary in this scenario. There are a few key features that seem to glare out:
1. Potential development of high pressure across southeast Canada (there seem to be some differences in this development and overall structure, strength, placement)
2. Potential development of an upper-level low across the eastern-tier of the Ohio Valley (which models seem to be in pretty strong agreement on)
3. Bermuda High
4. Actual strength of Henri moving through the weekend (this could be the biggest key overall)
I think a scenario like the GFS is showing is very low probability (but not impossible). I think direct impacts to SNE are low probability (not to say we may not see some showers, gusty winds) but surf will be very dangerous. The probability increases a bit heading out towards Cape Cod but perhaps not by much.
What scares me about this type of scenario is lead time...if this sort of solution is say still on the table tomorrow...or Friday but guidance continues to be poor agreement...a massive decision needs to be made about how to communicate this to the public. 2-3 days for preparations really isn't enough (especially in a more dire scenario).