The gist (if I'm being too terse, please inform):
1) Richard the Lionhearted does not die in 1199, instead he lives another nine years.
2) Henry VI also lives longer. This is only important as it relates to #3.
3) Otto of Saxony, OTL emperor Otto IV of the HRE, inherits Aquitaine on Eleanor's death. (Eleanor did intend this to happen, OTL Otto waived his claim to succeed her there when he became emperor).
4) Arthur succeeds Richard in 1208 and rules until 1240 or so.
Is it possible in these circumstances for the Angevins to hold Brittany along with Anjou and Normandy (see the map here -
http://www.englishmonarchs.co.uk/plantagenet.htm ) at least until after Arthur's death?
I'm not expecting it to last forever, and not necessarily very long, but can the English position be maintained there for the time being with Richard living longer and Arthur being a more successful king than John?
This is not meant as something very specific at this point - I'm just trying to sort out if that's within the resources available.
Holding on to Normandy and Anjou does not necessarily mean that Arthur doesn't pay homage to Philip for them or anything like that.