Cutting the 59 back to Euston means there will once again be no direct link (by bus OR Tube) between the country's busiest railway station and the Eurostar terminal.
The truncation of the 4 and 172 halves the number of bus routes (and therefore buses?) between Waterloo and the City - again an axis poorly served by the Tube. Still no buses on the direct route from Waterloo to the City via Blackfriars Bridge though.
I'm not sure this is the end for Fetter Lane as a bus route - the logical route if not going via Grays Inn Road is via Holborn Circus, not Ludgate Circus.
As for truncating the 172 at Aldwych, they usually do that anyway (leaving passengers from Waterloo further from the City than when they boarded), so no real change there.
The 40 is to be diverted over Blackfriars Bridge to replace the 45 and 388.