The new opportunities that are open to us affirm a need for many to continuously enrich themselves and if conversion is now regarded as an obvious fact, just like the need for a strong expatriation background, these modern requirements suggest a great adaptive capacity.
-"considered as" I thought "as" wasn't used in English after "considered"
-I would use "a" before "great adaptive capacity", - why not use "adaptability" rather than "adaptive capacity" here? => "...these modern requirements suggest a great adaptability."
Is 'affirm' not a better translation for 'affirmer' than 'claim'? I think what is meant here is more of a statement (affirmation) than a suggestion (claim)
'many body' is not correct English; 'many' would be good here, or 'many people'.
'to continuously enrich' -> 'to continuously enrich themselves' or 'continuously to enrich themselves' (many English people don't like split infinitives, but I don't know what Americans think of them)
'considered as' does not sound very natural to me; I would suggest 'regarded as'
as the need for... -> this is easier to understand if you say 'just like the need for..' or 'just as the need for...'
I agree with RedShadow on 'a great addaptive capacity'