Is removing the layover at Brockenhurst possible? I've been looking for an earlier thread where it was discussed (with no success) and I seem to recall it being considered impossible if the other services including XC all kept their timings. But as we know they are talking about a major rewrite for Dec 2018 so who knows...
Just like the current Poole train from Waterloo is completely the wrong choice for any main stations from Southampton westwards, because of the two "overtakes", then I expect this slow Weymouth is another that should not be advertised as a Weymouth service at Southampton...
Incidentally, it mentions that the truncated Poole train that becomes a Waterloo to Southampton semi fast will pick up calls at St Denys, (assume both ways) like it used to have a few years ago, an obvious impact of that (if all else stays the same) is that it will slow down the 2 hourly XC that usually catches it up around Eastleigh or Parkway.
Another thing that will only become obvious later is that during the afternoon peak some down direction Poole services (xx39s?) are diverted to become Portsmouth via Eastleigh. Wonder if they'll carry on with that arrangement, and so there isn't a gap in the Eastleigh to Southampton pattern, there'll still be a few short workings from Basingstoke I assume. Suppose it could also be portion worked and split like today's 1839 does.