After the late-1700s, I can find no references to cream dilute TBs (until the present). The cream lines either petered out or were misregistered as bays and chestnuts. It is possible that the color survived to the modern day that way, but it seems highly unlikely. You'd think, after all, that at least one golden coated horse might have been mentioned in the intervening 150+ years.

All modern cream dilute Thoroughbreds trace to one of two stallions (and sometimes both), Milkie and Glitter Please. Milkie, born in 1966, was regitered as chestnut, but was indisputably palomino. His dam, Tootsie T, was registered as brown, but she may in fact have been a sooty buckskin or smoky black. Her family is fairly obscure (and there are lines that trace back to Darcy's Yellow Turk), but it seems more likely that non-Thoroughbred blood bearing the cream gene was introduced at some point, accidentally or otherwise.

Glitter Please, born in 1982, likewise got his cream gene from his dam, Lucky Two Bits, who was registered as bay but who was in fact buckskin. Though less obscure than Milkie's distaff line, Glitter Please's is also mysterious in terms of the origin of the cream gene. Without photos of family members or DNA testing, it is impossible to determine where the color comes from. Regardless, both stallions were accepted and registered by the Jockey Club, and their offspring have been highly successful show horses in many disciplines. Their popularity has surged in the last decade, and their numbers have increased dramatically. Hopefully, the cream gene is here to stay this time around. :-)