1. That is obvious because the late Hidaka said back in 2008, "When Ash becomes a Pokemon Master, the show will end" which is now "Ash's adventures will end at least". Also, one of the leakers say the finale has an open ending but it's not 100% confirmed but extremely likely. As for the time skip, the statements from Yuyama and Yajima are confusing because Yuyama's statement "Ash is eternally ten years old" can be easily taken as "Ash will never become an adult".
2. I can also imagine Tierno trying to woo Serena but only to be left heartbroken when he discovers that she likes Ash. Brock witnesses this and tries to comfort Tierno by telling him that he himself has been in that similar situation.
Tierno: ♥ "Serena! Look at her! She's ten times more stunning than before! I'm going to ask her out on a date!" ♥ (rushes towards Serena) "Huh?"
Serena: (to herself while looking at her blue ribbon) ♥ "Congratulations on your World Pokemon Champion, Ash." (sigh) "Wait 'til we meet again when I reach to your level." ♥
Tierno: "You like Ash?"
Serena: "Huh? Did you just hear me talking?" "To be honest, yes. Ash is a very special person to me. He's very positive, full of energy, and never gives up until the very end. That's what I really love about him."
Tierno: "What do you know? My dream girl is actually in love with the new World Champion. What a bummer!"
Brock: "Yeah! Welcome to my life!"
Tierno: "Who are you?"
Brock: "My name is Brock and I know how you feel! I also went down that road as well! THE ROAD OF ROMANTIC REJECTION!! WWWAAAAAAHHHH!!!!"