Absolutely, but the direction of travel is towards Wycombe being an increasing part of that arc and being less part of the Thames Valley/London commuter belt*.
In 2001, 75% of workers living in Amersham, Wycombe, Slough, etc worked in that area - which had probably been the case for centuries. By 2011, Slough and suburbs ceased being part of that area, but the Aylesbury area had joined. Southern Bucks (save near Slough) is being less linked to the areas to the south, and more linked to areas to the north, and that is statistical fact.
It has naff all to do with the hills being between them - after all, there are hills in between Wycombe and Oxford (worse hills, in fact, given the lack of a handy gap southwest of Risborough), between Wycombe and most of Berkshire, and between Wycombe and London - it's surrounded by hills as it's in the middle of them! And don't forget that there's big hills between all the Chiltern valleys, but that hasn't stopped close ties between places in different valleys (eg Great Missenden and Wycombe, or Marlow and Wycombe) - and didn't in centuries gone by either. It has everything to do with the area's history (which is linked with being in the hills, but those hills have always been as permeable as the chalk they are made of!).
The historic barrier is fading away - do they even make chairs in Wycombe any more? Of the four B's Chesham was famous for making, baptists are the only ones still 'made' there - they don't make boots, beer or brushes there anymore, and haven't for some time. The light industry of the 'chalk' part of Bucks has given way to a knowledge-based economy - at home in London, the Thames Valley or the Varsity Arc. And in 'cheese' parts of Bucks, farming is much less important, with it too changing to a knowledge-based economy. The differences between the two halves of the county - formerly a metaphor for stark difference have lessened, and will only get less as time goes on. The county is homogenising, like the rest of the South East.
*Which, obviously given the definitions of TTWAs, is a misnomer as fewer than a quarter of workers living in Wycombe, Amersham, etc actually commute to the London TTWA.