I hope they stay very close to the D&D 5e rules.
Admittedly, they are far from perfect (Example: I hate that many classes can use shortbows but can't use longbows as if there was a huge difference).
But they have been tried and tested for years and have been very popular overall.
Once they start changing major rules, they'll open the box of pandora (like allowing to throw your boots as bonus action when it should only be allowed for offhand daggers in certain circumstances).
Changes will require changes that will require further changes.
In the end, we'll stray so far from the P&P ruleset that RtwP would seem like a minor cosmetic adjustment...
"Changing anything means more will change, means more will change."
That is the slippery slope fallacy.
I guess some people like at 5e as some holy grail. To me it is nothing more than a decent guideline. As long as I get a good game, I don't care for whatever ruleset is used.
That said, if 5e has reach rules, I didn't see any reach stat for the weapon in the demo. Actually, the little we've seen from the inventory shows a concerning lack of weapon data.
