I was curious to know who were the riders who had stayed at least 10 professional years with his current team, and these are several things I found.
I only consider professional contracts, I ignored years as trainee. I also included years in suspension or long-term injury, if any.
If I made mistakes, whether in facts or definition, or if I leave someone, feel free to correct the lists.
Current World Tour riders with longest uninterrupted stay in their current teams (* denotes rider who never rode professionally for any other team):
19th season: Imanol Erviti (MOV)*
18th: Mathieu Ladagnous (GFC)*
17th: Robert Gesink (TJV), Jose Joaquin Rojas (MOV)
16th: Jos van Emden (TJV)
14th: Cesare Benedetti (BOH), Steven Kruijswijk (TJV), Thibaut Pinot (GFC)*, Geraint Thomas (IGD), Diego Ulissi (UAE)*
13th: Mikael Cherel (ACT)
12th: Arnaud Demare (FDJ)*, Luke Durbridge (JAY), Dmitriy Gruzdev (AST), Michael Hepburn (JAY), Salvatore Puccio (IGD)*, Luke Rowe (IGD)*
11th: Alexey Lutsenko (AST), Pieter Serry (SOQ)
10th: Julian Alaphilippe (SOQ), Anthony Delaplace (ARK), Olivier LeGac (GFC)*, Jasper Stuyven (LTK), Simon Yates (JAY)*
There are also current WT riders who are in their 10th or more seasons in their current teams, but interrupted by stint(s) in other team(s) before coming back:
14th: Andrey Zeits (AST)
12th: Dries Devenyns (SOQ), Ben Swift (IGD)
10th: Laurent Pichon (ARK)
Lastly, there are riders who spent more than 10 seasons with a team, but now are riding for other teams:
11 - Andrey Amador (CDE, MOV, now EFE), Nicolas Edet (COF, now ARK), Tim Wellens (LTB, LTD, now UAE)
10 - Niklas Arndt (ARG, GIA, SUN, now TBV), Simon Geschke (SKI, ARG, GIA etc, now COF), Zdenek Stybar (QS, now JAY), Greg Van Avermaet (BMC, now ACT),