Okay, then what I thought could be a loophole is not.
What I thought was :
- Before the decreto 616/2010 : The law 25.871 was using decretos published before (from 1977,1994,1995,...) hence the hectic situation. Furthermore arts 122 and 124 of law 25.871 tell that although the new law creates a new situation, previous decretos would still apply until a new one was passed.
- After the decreto 616/2010 : art.2 tells that this decreto derogates to previous decretos (1977,94,95...) which is consistent with arts 122 and 124 of ley 25.871.
Therefore it's like if a new situation was created from the scratch, hence the essence of the new decreto.
Now I was surprised to read art.24 of the new decreto :
ARTICULO 24.- Los extranjeros que ingresen al país como "residentes transitorios" podrán ser admitidos en las subcategorías establecidas por el artículo 24 de la Ley Nº 25.871, con los siguientes alcances:
a) Turistas: quienes ingresen con propósito de descanso o esparcimiento, con plazo de permanencia de hasta TRES (3) meses, prorrogables por otro período similar
while nowhere could be found a text mentionning that turists (e.g.) could not stay for more than 180 days per year.
Of course, it could be argued that a turist staying in Argentina for 340 days a year could not reasonably be considered as a turist, but still, no precise mention has been made.
So, in fact, I wondered if a turist could legally (everything that is not forbidden by law is legal) come here for 90 days, prorrogate the visa for +90 days, exit the country for 1 day, reenter as a turist for a new cycle (like before in fact).
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Asking bajo-cero, he replied something I had overlooked (anyway it's about the same thing about defining a turist that would stay here for 340 days a year) :
ARTICULO 61.- Cuando se verifique que un extranjero hubiere desnaturalizado los motivos que autorizaron su ingreso al territorio argentino o permaneciera en éste vencido el plazo de permanencia acordado,
According to him, I agree, it's even less permissive since the authorities could even annoy someone who would stay here only 180 days a year.
.... So no loophole, sorry