Yes, Universal should bring it back.
LBTFan13 and LBTDiclonius have made good points.
LBT XIII was crap (haven't actually seen that one, but have seen clips from it) It would be terrible for the movie series to go out with the yellowbellies. Come on.
And "Diclonius" also made a good point that I liked about having past characters return.
Personally I really reallly want to see Pterano again. He is much more popular of a character than Rinkus & Sierra are (I REALLY love him so much, and most of you guys do, too!) after all... Pterano is not a true villain, but more of an anti-hero.... he started out bad but then he became good at the end of "cold fire".

Now, Rinkus & Sierra were bad all the way through. (especially Sierra). Rinkus was really funny, but then he turned mean starting where Pterano was singing "Very Important Creature" And the "little gnat slap" he gave to Petrie, sending him crashing down into the water was mean, too.
*Although Rob Paulsen would be fairly easy for Universal to get ahold of*... and Paulsen did voice other LBT characters like Spike, Guido, and Strut. I would enjoy seeing Rinkus again, but not as much as Pterano.
Sooo in summary...
I think Pterano's got a great chance of returning (I can only hope they can get Michael York to voice Pterano again) And if they can't, then I really hope they find a very good new actor to voice Pterano.
I can only pray and pray HARD that Pterano DOES return in the next LBT movie if there are going to be any more.
(If there is, there is

....and, well....if there isn't, there isn't

) I'll try not to get too upset about it.
I have a couple of titles I thought of IF the next movie will have Pterano in it.
"The Land Before Time XIV: "Pterano's Return", or maybe
"The Land Before Time XIV: "The Return of Pterano"
And even if the next movie isn't mainly focused on Pterano, but he still appears in it... that would be great, too.
But just letting LBT go out with a crappy movie with the yellowbellies would be a terrible shame.