There are many other, lesser factors at work, but taken together, all tend toward standardization, especially as the older speakers die off.
( There ( ( are ( ( many other ) ( , ( ( ( lesser factors ) ( at work ) ) ( , ( but ( ( ( taken together ) ( , ( ( all ( tend ( toward standardization ) ) ) , ) ) ) ( especially ( as ( ( the ( older speakers ) ) ( die off ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (EX There)) (VP (VBP are) (UCP (ADJP (JJ many) (JJ other)) (, ,) (X (NP (NP (JJR lesser) (NNS factors)) (PP (IN at) (NP (NN work))))) (, ,) (CC but) (VP (VBN taken) (PRT (RP together)) (PRN (, ,) (S (NP (DT all)) (VP (VBP tend) (PP (IN toward) (NP (NN standardization))))) (, ,)) (SBAR (RB especially) (IN as) (S (NP (DT the) (JJR older) (NNS speakers)) (VP (VBP die) (PRT (RP off)))))))) (. .)))
There are no older speakers.
( There ( ( are ( ( no older ) speakers ) ) . ) )
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (ADJP (DT no) (JJR older)) (NNS speakers))) (. .)))