I have uploaded a digi pic of Pembroke Cottage  taken last summer whilst out on a bike ride to survey neighbouring Moat Cottage in Hartley Wespall, North East Hampshire (that's another story)
To say that Pembroke Cottage is 600 years old is probably a bit of an exaggeration - Dan Miles has now dendrodated the cruck framed part of the cottage (on the left) to 1414 and so it's actually only 598 years old. The box frame (on the right) is much newer and probably dates from the mid to late 1400's.
A more up to date 3D image of the Pembroke Cottage box frame can be found in OBR Newsletter No 44 where this features in an illustrated timber frame glossary in the article on pages 4 and 5 - "What's in a word". Check out the other Oxfordshire Buildings Record Newsletters that can be downloaded for free from http://obr.org.uk
I think that old buildings tend to be reivented with the passage of time as bits decay or are removed and replaced and not necessarily with like for like materials (what evidence of this can you see in the photo). It would be very difficult to forecast just how long a timber framed building might survive or at what point in percentage of original materials remaining that we can still call it the same cottage. The secret of long term survival would appear to lie strangely enough with poverty and and to a certain extent in neglect. Generally the worst things happen to these veteran buildings when new upwardly mobile owners move in and begin to assert their will on the component parts of our built heritage sometimes causing significant damage and loss. This is nothing new and it is known to have happened over the centuries as fortunes wax and wane but at least these days there is now a due process to be followed when making changes to historic buildings.
The version of Pembroke Cottage constructed by Tom Musco in Royalston, Massachussetts (up on the border with New Hampshire) was made using local vernacular materials instead of English oak and so this included such timbers as Eastern white pine, Eastern Hemlock, Red Oak and some Yellow Birch. The frame is clad and so is to a certain extent protected from the elements however the internal army of carpenter ants is ever present and remain focussed on their task to recycle dead wood.
It would be wonderful if Tom or someone living local to Pembroke Cottage II could take and post a pic of his wonderful creation. I am sure that it will outlive us all and then, with our passing, so will the joys and sorrows associated with this kind of human endeavour be forgotten, with only the building remaining, holding tight lipped onto the true story associated with the creation of one of New England's future historic buildings.